diff --git a/client/css/colors.styl b/client/css/colors.styl
index b2aabc9a..da5f72ed 100644
--- a/client/css/colors.styl
+++ b/client/css/colors.styl
@@ -33,6 +33,9 @@ $new-tag-background-color = #DFC
 $new-tag-text-color = black
 $implied-tag-background-color = #FFC
 $implied-tag-text-color = black
+$tag-suggestions-background-color = $window-color
+$tag-suggestions-header-color = #EEE
+$tag-suggestions-border-color = #AAA
 $duplicate-tag-background-color = #FDC
 $duplicate-tag-text-color = black
 $note-overlay-background-color = rgba(255, 255, 255, 0.3)
diff --git a/client/css/forms.styl b/client/css/forms.styl
index 2f8c6e49..bb4c96fc 100644
--- a/client/css/forms.styl
+++ b/client/css/forms.styl
@@ -174,6 +174,7 @@ input:disabled
     cursor: not-allowed
 
 div.tag-input
+    position: relative
     li
         transition: background-color 0.5s linear
         &.implication
@@ -188,6 +189,71 @@ div.tag-input
     ul
         margin-top: 0.2em
 
+    .tag-suggestions
+        position: absolute
+        z-index: 5
+        top: 0
+        left: 100%
+
+        &:not(.shown)
+            display: none
+
+        .close
+            float: right
+            color: $inactive-link-color
+        .wrapper
+            margin-left: 0.5em
+            background: $tag-suggestions-background-color
+            border: 1px solid $tag-suggestions-border-color
+            width: 15em
+            word-break: break-all
+            p
+                background: $tag-suggestions-header-color
+                padding: 0.2em 1em
+                margin: 0
+            ul
+                margin: 0
+                overflow-y: auto
+                overflow-x: none
+                max-height: 20em
+                padding: 0.5em 1em 0 1em
+                li:last-child
+                    border-bottom: 0.5em solid alpha($tag-suggestions-background-color, 0)
+                li
+                    margin: 0
+                    font-size: 90%
+                    line-height: 1.3
+                    a, span
+                        display: inline-block
+                        vertical-align: bottom
+                    .add-tag
+                        white-space: nowrap
+                        overflow: hidden
+                        max-width: 10em
+                        text-overflow: ellipsis
+                    .tag-weight
+                        margin: 0 1em 0 0
+            p
+                margin: 0
+        &:before
+            margin-left: 0.5em
+            margin-top: 0.5em
+            position: absolute
+            display: block
+            background: $tag-suggestions-header-color
+            border-left: 1px solid $tag-suggestions-border-color
+            border-bottom: 1px solid $tag-suggestions-border-color
+            width: 0.707107em
+            height: 0.707107em
+            content: ' '
+            transform: rotate(45deg)
+            transform-origin: 0 0%
+        .append
+            color: $inactive-link-color
+            margin-left: 0.7em
+            font-size: 90%
+
+
 ul.compact-tags
     line-height: 130%
     word-break: break-all
@@ -195,9 +261,9 @@ ul.compact-tags
         margin: 0
     i
         padding-right: 0.4em
-    .count
+    .append
         color: $inactive-link-color
-        padding-left: 0.7em
+        margin-left: 0.7em
         font-size: 90%
 
 div.tag-relations
@@ -285,7 +351,7 @@ input::-moz-focus-inner
  * File dropper
  */
 .file-dropper
-    background: white
+    background: $window-color
     border: 3px dashed #eee
     padding: 0.3em 0.5em
     line-height: 140%
@@ -307,7 +373,7 @@ input[type=file]:focus+.file-dropper,
 .autocomplete
     position: absolute
     z-index: 10
-    background: white
+    background: $window-color
     border: 2px solid $main-color
     display: none
     font-size: 0.95em
diff --git a/client/html/post_readonly_sidebar.tpl b/client/html/post_readonly_sidebar.tpl
index 0492b7e0..af3bf3e8 100644
--- a/client/html/post_readonly_sidebar.tpl
+++ b/client/html/post_readonly_sidebar.tpl
@@ -80,7 +80,7 @@
                         --><% if (ctx.canListPosts) { %><!--
                             --></a><!--
                         --><% } %><!--
-                        --><span class='count'><%- ctx.getTagUsages(tag) %></span><!--
+                        --><span class='append'><%- ctx.getTagUsages(tag) %></span><!--
                     --></li><!--
                 --><% } %><!--
             --></ul>
diff --git a/client/js/controls/tag_input_control.js b/client/js/controls/tag_input_control.js
index 1c06792e..7abc5d6d 100644
--- a/client/js/controls/tag_input_control.js
+++ b/client/js/controls/tag_input_control.js
@@ -13,6 +13,7 @@ const KEY_RETURN = 13;
 const SOURCE_INIT = 'init';
 const SOURCE_IMPLICATION = 'implication';
 const SOURCE_USER_INPUT = 'user-input';
+const SOURCE_SUGGESTION = 'suggestions';
 
 function _fadeOutListItemNodeStatus(listItemNode) {
     if (listItemNode.classList.length) {
@@ -29,10 +30,55 @@ function _fadeOutListItemNodeStatus(listItemNode) {
     }
 }
 
+class SuggestionList {
+    constructor() {
+        this._suggestions = {};
+        this._banned = [];
+    }
+
+    clear() {
+        this._suggestions = {};
+    }
+
+    get length() {
+        return Object.keys(this._suggestions).length;
+    }
+
+    set(suggestion, weight) {
+        if (this._suggestions.hasOwnProperty(suggestion)) {
+            weight = Math.max(weight, this._suggestions[suggestion]);
+        }
+        this._suggestions[suggestion] = weight;
+    }
+
+    ban(suggestion) {
+        this._banned.push(suggestion);
+    }
+
+    getAll() {
+        let tuples = [];
+        for (let suggestion of Object.keys(this._suggestions)) {
+            if (!this._banned.includes(suggestion)) {
+                const weight = this._suggestions[suggestion];
+                tuples.push([suggestion, weight.toFixed(1)]);
+            }
+        }
+        tuples.sort((a, b) => {
+            let weightDiff = b[1] - a[1];
+            let nameDiff = a[0].localeCompare(b[0]);
+            return weightDiff == 0 ? nameDiff : weightDiff;
+        });
+        return tuples.map(tuple => {
+            return {tagName: tuple[0], weight: tuple[1]};
+        });
+    }
+}
+
 class TagInputControl extends events.EventTarget {
     constructor(sourceInputNode) {
         super();
         this.tags = [];
+        this._suggestions = new SuggestionList();
 
         this._relationsTemplate = views.getTemplate('tag-relations');
         this._sourceInputNode = sourceInputNode;
@@ -64,6 +110,20 @@ class TagInputControl extends events.EventTarget {
             'paste', e => this._evtInputPaste(e));
         this._editAreaNode.appendChild(this._tagInputNode);
 
+        this._suggestionsNode = views.htmlToDom(
+            '<div class="tag-suggestions">' +
+            '<div class="wrapper">' +
+            '<p>Suggested tags<a class="close" href="#">×</a></p>' +
+            '<ul></ul>' +
+            '</div>' +
+            '</div>');
+        this._editAreaNode.appendChild(this._suggestionsNode);
+        this._editAreaNode.querySelector('a.close').addEventListener(
+            'click', e => {
+                e.preventDefault();
+                this._closeSuggestionsPopup();
+            });
+
         this._tagListNode = views.htmlToDom('<ul class="compact-tags"></ul>');
         this._editAreaNode.appendChild(this._tagListNode);
 
@@ -112,7 +172,7 @@ class TagInputControl extends events.EventTarget {
 
         // XXX: perhaps we should aggregate suggestions from all implications
         // for call to the _suggestRelations
-        if ([SOURCE_USER_INPUT, SOURCE_IMPLICATION].includes(source)) {
+        if (source !== SOURCE_INIT) {
             for (let otherTagName of tags.getAllImplications(tagName)) {
                 this.addTag(otherTagName, SOURCE_IMPLICATION);
             }
@@ -144,12 +204,14 @@ class TagInputControl extends events.EventTarget {
 
     _evtTagAdded(e) {
         const tagName = e.detail.tagName;
+        const actualTag = tags.getTagByName(tagName);
         let listItemNode = this._getListItemNodeFromTagName(tagName);
-        if (listItemNode) {
+        const alreadyAdded = !!listItemNode;
+        if (alreadyAdded) {
             listItemNode.classList.add('duplicate');
         } else {
             listItemNode = this._createListItemNode(tagName);
-            if (!tags.getTagByName(tagName)) {
+            if (!actualTag) {
                 listItemNode.classList.add('new');
             }
             if (e.detail.source === SOURCE_IMPLICATION) {
@@ -158,6 +220,11 @@ class TagInputControl extends events.EventTarget {
             this._tagListNode.prependChild(listItemNode);
         }
         _fadeOutListItemNodeStatus(listItemNode);
+
+        if ([SOURCE_USER_INPUT, SOURCE_SUGGESTION].includes(e.detail.source) &&
+                actualTag) {
+            this._loadSuggestions(actualTag);
+        }
     }
 
     _evtTagRemoved(e) {
@@ -201,43 +268,55 @@ class TagInputControl extends events.EventTarget {
         this._hideAutoComplete();
         this.addMultipleTags(text, SOURCE_USER_INPUT);
         this._tagInputNode.value = '';
-        // TODO: suggest relations!
     }
 
     _createListItemNode(tagName) {
         const actualTag = tags.getTagByName(tagName);
         const className = actualTag ?
             misc.makeCssName(actualTag.category, 'tag') :
-            '';
+            null;
+        if (actualTag) {
+            tagName = actualTag.names[0];
+        }
 
-        const tagLinkNode = views.htmlToDom(
-            views.makeNonVoidElement(
-                'a',
-                {
-                    class: className,
-                    href: '/tag/' + encodeURIComponent(tagName),
-                },
-                '<i class="fa fa-tag"></i>'));
+        const tagLinkNode = document.createElement('a');
+        if (className) {
+            tagLinkNode.classList.add(className);
+        }
+        tagLinkNode.setAttribute(
+            'href',  '/tag/' + encodeURIComponent(tagName));
+        const tagIconNode = document.createElement('i');
+        tagIconNode.classList.add('fa');
+        tagIconNode.classList.add('fa-tag');
+        tagLinkNode.appendChild(tagIconNode);
 
-        const searchLinkNode = views.htmlToDom(
-            views.makeNonVoidElement(
-                'a',
-                {
-                    class: className,
-                    href: '/posts/query=' + encodeURIComponent(tagName),
-                },
-                actualTag ? actualTag.names[0] : tagName));
+        const searchLinkNode = document.createElement('a');
+        if (className) {
+            searchLinkNode.classList.add(className);
+        }
+        searchLinkNode.setAttribute(
+            'href', '/posts/query=' + encodeURIComponent(tagName));
+        searchLinkNode.textContent = tagName;
+        searchLinkNode.addEventListener('click', e => {
+            e.preventDefault();
+            if (actualTag) {
+                this._suggestions.clear();
+                this._loadSuggestions(actualTag);
+            } else {
+                this._closeSuggestionsPopup();
+            }
+        });
 
         const usagesNode = views.htmlToDom(
             views.makeNonVoidElement(
                 'span',
-                {class: 'count'},
+                {class: 'append'},
                 actualTag ? actualTag.usages : 0));
 
         const removalLinkNode = views.htmlToDom(
             views.makeNonVoidElement(
                 'a',
-                {href: '#', class: 'count'},
+                {href: '#', class: 'append'},
                 '×'));
         removalLinkNode.addEventListener('click', e => {
             e.preventDefault();
@@ -253,6 +332,95 @@ class TagInputControl extends events.EventTarget {
         return listItemNode;
     }
 
+    _loadSuggestions(tag) {
+        api.get('/tag-siblings/' + tag.names[0], {noProgress: true})
+            .then(response => {
+                return Promise.resolve(response.results);
+            }, response => {
+                return Promise.resolve([]);
+            }).then(siblings => {
+                let maxSiblingOccurrences = Math.max(
+                    1, ...siblings.map(s => s.occurrences));
+                for (let sibling of siblings) {
+                    this._suggestions.set(
+                        sibling.tag.names[0],
+                        sibling.occurrences * 4.9 / maxSiblingOccurrences);
+                }
+                for (let suggestion of tag.suggestions || []) {
+                    this._suggestions.set(suggestion, 5);
+                }
+                if (this._suggestions.length) {
+                    this._openSuggestionsPopup();
+                } else {
+                    this._closeSuggestionsPopup();
+                }
+            });
+    }
+
+    _refreshSuggestionsPopup() {
+        if (!this._suggestionsNode.classList.contains('shown')) {
+            return;
+        }
+        const listNode = this._suggestionsNode.querySelector('ul');
+        while (listNode.firstChild) {
+            listNode.removeChild(listNode.firstChild);
+        }
+        for (let tuple of this._suggestions.getAll()) {
+            const tagName = tuple.tagName;
+            const weight = tuple.weight;
+            if (this.isTaggedWith(tagName)) {
+                continue;
+            }
+
+            const actualTag = tags.getTagByName(tagName);
+            const addLinkNode = document.createElement('a');
+            addLinkNode.textContent = tagName;
+            addLinkNode.setAttribute('href', '#');
+            addLinkNode.classList.add('add-tag');
+            if (actualTag) {
+                addLinkNode.classList.add(
+                    misc.makeCssName(actualTag.category, 'tag'));
+            }
+            addLinkNode.addEventListener('click', e => {
+                e.preventDefault();
+                listNode.removeChild(listItemNode);
+                this.addTag(tagName, SOURCE_SUGGESTION);
+            });
+
+            const weightNode = document.createElement('span');
+            weightNode.classList.add('tag-weight');
+            weightNode.classList.add('append');
+            weightNode.textContent = weight;
+
+            const removeLinkNode = document.createElement('a');
+            removeLinkNode.classList.add('remove-tag');
+            removeLinkNode.classList.add('append');
+            removeLinkNode.textContent = '×';
+            removeLinkNode.setAttribute('href', '#');
+            removeLinkNode.addEventListener('click', e => {
+                e.preventDefault();
+                listNode.removeChild(listItemNode);
+                this._suggestions.ban(tagName);
+            });
+
+            const listItemNode = document.createElement('li');
+            listItemNode.appendChild(weightNode);
+            listItemNode.appendChild(addLinkNode);
+            listItemNode.appendChild(removeLinkNode);
+            listNode.appendChild(listItemNode);
+        }
+    }
+
+    _closeSuggestionsPopup() {
+        this._suggestions.clear();
+        this._suggestionsNode.classList.remove('shown');
+    }
+
+    _openSuggestionsPopup() {
+        this._suggestionsNode.classList.add('shown');
+        this._refreshSuggestionsPopup();
+    }
+
     _hideAutoComplete() {
         this._autoCompleteControl.hide();
     }