diff --git a/app/assets/javascripts/discourse.js b/app/assets/javascripts/discourse.js
index 4b845c4c8..d05de2e48 100644
--- a/app/assets/javascripts/discourse.js
+++ b/app/assets/javascripts/discourse.js
@@ -105,19 +105,20 @@ Discourse = Ember.Application.createWithMixins(Discourse.Ajax, {
     $('#main').on('click.discourse', 'a', function(e) {
       if (e.isDefaultPrevented() || e.shiftKey || e.metaKey || e.ctrlKey) { return; }
 
-      var $currentTarget = $(e.currentTarget);
-      var href = $currentTarget.attr('href');
-      if (!href) { return; }
-      if (href === '#') { return; }
-      if ($currentTarget.attr('target')) { return; }
-      if ($currentTarget.data('auto-route')) { return; }
+      var $currentTarget = $(e.currentTarget),
+          href = $currentTarget.attr('href');
 
-      // If it's an ember #link-to skip it
-      if ($currentTarget.hasClass('ember-view')) { return; }
-
-      if ($currentTarget.hasClass('lightbox')) { return; }
-      if (href.indexOf("mailto:") === 0) { return; }
-      if (href.match(/^http[s]?:\/\//i) && !href.match(new RegExp("^http:\\/\\/" + window.location.hostname, "i"))) { return; }
+      if (!href ||
+          href === '#' ||
+          $currentTarget.attr('target') ||
+          $currentTarget.data('ember-action') ||
+          $currentTarget.data('auto-route') ||
+          $currentTarget.hasClass('ember-view') ||
+          $currentTarget.hasClass('lightbox') ||
+          href.indexOf("mailto:") === 0 ||
+          (href.match(/^http[s]?:\/\//i) && !href.match(new RegExp("^http:\\/\\/" + window.location.hostname, "i")))) {
+         return;
+      }
 
       e.preventDefault();
       Discourse.URL.routeTo(href);
diff --git a/app/assets/javascripts/discourse/controllers/poster_expansion_controller.js b/app/assets/javascripts/discourse/controllers/poster_expansion_controller.js
new file mode 100644
index 000000000..61cab9438
--- /dev/null
+++ b/app/assets/javascripts/discourse/controllers/poster_expansion_controller.js
@@ -0,0 +1,30 @@
+/**
+  A controller for expanding information about a poster.
+
+  @class PosterExpansion
+  @extends Discourse.ObjectController
+  @namespace Discourse
+  @module Discourse
+**/
+Discourse.PosterExpansionController = Discourse.ObjectController.extend({
+  needs: ['topic'],
+
+  show: function(user, post) {
+    this.setProperties({model: user, post: post});
+  },
+
+  close: function() {
+    this.set('model', null);
+  },
+
+  actions: {
+    togglePosts: function(user) {
+      var postStream = this.get('controllers.topic.postStream');
+      postStream.toggleParticipant(user.get('username'));
+      this.close();
+    }
+  }
+
+});
+
+
diff --git a/app/assets/javascripts/discourse/models/post_stream.js b/app/assets/javascripts/discourse/models/post_stream.js
index c8c6636fd..c4c0217d5 100644
--- a/app/assets/javascripts/discourse/models/post_stream.js
+++ b/app/assets/javascripts/discourse/models/post_stream.js
@@ -133,7 +133,6 @@ Discourse.PostStream = Em.Object.extend({
 
   hasNoFilters: Em.computed.empty('filterDesc'),
 
-
   /**
     Returns the window of posts above the current set in the stream, bound to the top of the stream.
     This is the collection we'll ask for when scrolling upwards.
diff --git a/app/assets/javascripts/discourse/models/user.js b/app/assets/javascripts/discourse/models/user.js
index 627918c61..b3fee4385 100644
--- a/app/assets/javascripts/discourse/models/user.js
+++ b/app/assets/javascripts/discourse/models/user.js
@@ -259,7 +259,6 @@ Discourse.User = Discourse.Model.extend({
         json.user.invited_by = Discourse.User.create(json.user.invited_by);
       }
 
-
       user.setProperties(json.user);
       return user;
     });
@@ -297,6 +296,17 @@ Discourse.User = Discourse.Model.extend({
 Discourse.User.reopenClass(Discourse.Singleton, {
 
 
+  /**
+    Find a `Discourse.User` for a given username.
+
+    @method findByUsername
+    @returns {Promise} a promise that resolves to a `Discourse.User`
+  **/
+  findByUsername: function(username) {
+    var user = Discourse.User.create({username: username});
+    return user.findDetails();
+  },
+
   /**
     The current singleton will retrieve its attributes from the `PreloadStore`
     if it exists. Otherwise, no instance is created.
@@ -325,7 +335,6 @@ Discourse.User.reopenClass(Discourse.Singleton, {
     });
   },
 
-
   /**
     Checks if given username is valid for this email address
 
diff --git a/app/assets/javascripts/discourse/routes/topic_route.js b/app/assets/javascripts/discourse/routes/topic_route.js
index 6865e340d..375a33cf4 100644
--- a/app/assets/javascripts/discourse/routes/topic_route.js
+++ b/app/assets/javascripts/discourse/routes/topic_route.js
@@ -13,6 +13,14 @@ Discourse.TopicRoute = Discourse.Route.extend({
   actions: {
     // Modals that can pop up within a topic
 
+    showPosterExpansion: function(post) {
+      var self = this;
+
+      Discourse.User.findByUsername(post.get('username')).then(function (user) {
+        self.controllerFor('posterExpansion').show(user, post);
+      });
+    },
+
     showFlags: function(post) {
       Discourse.Route.showModal(this, 'flag', post);
       this.controllerFor('flag').setProperties({ selected: null });
@@ -80,9 +88,10 @@ Discourse.TopicRoute = Discourse.Route.extend({
 
     // Clear the search context
     this.controllerFor('search').set('searchContext', null);
+    this.controllerFor('posterExpansion').set('model', null);
 
-    var topicController = this.controllerFor('topic');
-    var postStream = topicController.get('postStream');
+    var topicController = this.controllerFor('topic'),
+        postStream = topicController.get('postStream');
     postStream.cancelFilter();
 
     topicController.set('multiSelect', false);
diff --git a/app/assets/javascripts/discourse/templates/post.js.handlebars b/app/assets/javascripts/discourse/templates/post.js.handlebars
index 516556941..534080598 100644
--- a/app/assets/javascripts/discourse/templates/post.js.handlebars
+++ b/app/assets/javascripts/discourse/templates/post.js.handlebars
@@ -19,9 +19,9 @@
     <div class='topic-meta-data span2'>
       {{#unless userDeleted}}
         <div {{bindAttr class=":contents byTopicCreator:topic-creator"}}>
-          <a href='{{unbound usernameUrl}}'>{{avatar this imageSize="large"}}</a>
-          <h3 {{bindAttr class="staff new_user"}}><a href='{{unbound usernameUrl}}'>{{breakUp username}}</a></h3>
-          {{#if user_title}}<div class="user-title">{{user_title}}</div>{{/if}}
+          <a href='{{unbound usernameUrl}}' {{action showPosterExpansion this}}>{{avatar this imageSize="large"}}</a>
+          <h3 {{bindAttr class="staff new_user"}}><a href='{{unbound usernameUrl}}' {{action showPosterExpansion this}}>{{breakUp username}}</a></h3>
+          {{#if user_title}}<div class="user-title" {{action showPosterExpansion this}}>{{user_title}}</div>{{/if}}
         </div>
       {{else}}
         <div class="contents">
diff --git a/app/assets/javascripts/discourse/templates/poster_expansion.handlebars b/app/assets/javascripts/discourse/templates/poster_expansion.handlebars
new file mode 100644
index 000000000..185af36de
--- /dev/null
+++ b/app/assets/javascripts/discourse/templates/poster_expansion.handlebars
@@ -0,0 +1,18 @@
+{{#if model}}
+  {{avatar model imageSize="huge"}}
+
+  <h1>{{username}}</h1>
+  <h2>{{name}}</h2>
+  <h3>{{i18n last_post}}: {{unboundDate last_posted_at}}</h3>
+
+  <div class='bottom'>
+    {{#if bio_cooked}}<div class='bio'>{{{bio_cooked}}}</div>{{/if}}
+
+    <button class='btn'><i class='icon icon-envelope'></i>{{i18n user.private_message}}</button>
+
+    {{#link-to 'user' model class="btn"}}<i class='icon icon-user'></i>{{i18n user.profile}}{{/link-to}}
+
+    <button class='btn' {{action togglePosts this}}><i class='icon icon-filter'></i>{{i18n topic.filter_to username="username"}}</button>
+  </div>
+
+{{/if}}
diff --git a/app/assets/javascripts/discourse/templates/topic.js.handlebars b/app/assets/javascripts/discourse/templates/topic.js.handlebars
index c6c17ffde..c81775e2f 100644
--- a/app/assets/javascripts/discourse/templates/topic.js.handlebars
+++ b/app/assets/javascripts/discourse/templates/topic.js.handlebars
@@ -125,6 +125,8 @@
 </div>
 
 {{render share}}
+{{render posterExpansion}}
+
 {{#if currentUser.enable_quoting}}
   {{render quoteButton}}
 {{/if}}
@@ -132,3 +134,4 @@
 {{#if currentUser.staff}}
   {{render topicAdminMenu content}}
 {{/if}}
+
diff --git a/app/assets/javascripts/discourse/views/poster_expansion_view.js b/app/assets/javascripts/discourse/views/poster_expansion_view.js
new file mode 100644
index 000000000..36fb39d28
--- /dev/null
+++ b/app/assets/javascripts/discourse/views/poster_expansion_view.js
@@ -0,0 +1,43 @@
+/**
+  Shows expanded details for a poster
+
+  @class PosterExpansionView
+  @namespace Discourse
+  @module Discourse
+**/
+Discourse.PosterExpansionView = Discourse.View.extend({
+  elementId: 'poster-expansion',
+  classNameBindings: ['controller.model::hidden'],
+
+  // Position the expansion when the model changes
+  _modelChanged: function() {
+    var post = this.get('controller.post'),
+        self = this;
+
+    Em.run.schedule('afterRender', function() {
+      if (post) {
+        var $post = $('#' + post.get('postElementId')),
+            $avatar = $('.topic-meta-data img.avatar', $post),
+            position = $avatar.offset();
+
+        position.left += $avatar.width() + 5;
+        self.$().css(position);
+      }
+    });
+
+  }.observes('controller.model'),
+
+  didInsertElement: function() {
+    var self = this;
+    $('html').on('mousedown.outside-poster-expansion', function(e) {
+      if (self.$().has(e.target).length !== 0) { return; }
+      self.get('controller').set('model', null);
+      return true;
+    });
+  },
+
+  willDestroyElement: function() {
+    $('html').off('mousedown.outside-poster-expansion');
+  }
+
+});
\ No newline at end of file
diff --git a/app/assets/stylesheets/desktop/poster_expansion.scss b/app/assets/stylesheets/desktop/poster_expansion.scss
new file mode 100644
index 000000000..8a3a62891
--- /dev/null
+++ b/app/assets/stylesheets/desktop/poster_expansion.scss
@@ -0,0 +1,51 @@
+// styles that apply to the "share" popup when sharing a link to a post or topic
+
+@import "common/foundation/variables";
+@import "common/foundation/mixins";
+
+#poster-expansion {
+  position: absolute;
+  left: 20px;
+  z-index: 990;
+  @include border-radius-all(3px);
+  @include box-shadow(1px 1px 5px $darkish_gray);
+  background-color: $white;
+  padding: 7px 7px 6px 7px;
+  width: 400px;
+
+  h1 {
+    font-size: 30px;
+    line-height: 33px;
+    margin-bottom: 8px;
+  }
+
+  h2 {
+    font-size: 20px;
+    line-height: 22px;
+    font-weight: normal;
+  }
+
+  h3 {
+    font-size: 13px;
+    font-weight: normal;
+    margin-top: 5px;
+  }
+
+  .bottom {
+    clear: both;
+    padding-top: 10px;
+  }
+
+  img.avatar {
+    float: left;
+    padding-right: 10px;
+  }
+
+  p {
+    margin: 0 0 5px 0;
+  }
+
+  button {
+    margin: 0 0 7px 0;
+  }
+}
diff --git a/app/controllers/topics_controller.rb b/app/controllers/topics_controller.rb
index 1872e1ea5..8f4a8996e 100644
--- a/app/controllers/topics_controller.rb
+++ b/app/controllers/topics_controller.rb
@@ -30,6 +30,8 @@ class TopicsController < ApplicationController
 
     opts = params.slice(:username_filters, :filter, :page, :post_number)
 
+    opts[:username_filters] = [opts[:username_filters]] if opts[:username_filters].is_a?(String)
+
     begin
       @topic_view = TopicView.new(params[:id] || params[:topic_id], current_user, opts)
     rescue Discourse::NotFound
diff --git a/config/locales/client.en.yml b/config/locales/client.en.yml
index 7891f01c0..370a4b994 100644
--- a/config/locales/client.en.yml
+++ b/config/locales/client.en.yml
@@ -581,6 +581,7 @@ en:
       title: Topic Rank Details
 
     topic:
+      filter_to: "Toggle only posts by {{username}} in this topic"
       create_in: 'Create {{categoryName}} Topic'
       create: 'Create Topic'
       create_long: 'Create a new Topic'
diff --git a/test/javascripts/models/user_test.js b/test/javascripts/models/user_test.js
index 0414ef44e..c25ab80fb 100644
--- a/test/javascripts/models/user_test.js
+++ b/test/javascripts/models/user_test.js
@@ -25,3 +25,15 @@ test("isAllowedToUploadAFile", function() {
   user.setProperties({ admin: false, moderator: true });
   ok(user.isAllowedToUploadAFile("image"), "moderator can always upload a file");
 });
+
+
+asyncTestDiscourse("findByUsername", function() {
+  expect(3);
+
+  Discourse.User.findByUsername('eviltrout').then(function (user) {
+    present(user);
+    equal(user.get('username'), 'eviltrout', 'it has the correct username');
+    equal(user.get('name'), 'Robin Ward', 'it has the full name since it has details');
+    start();
+  });
+});
\ No newline at end of file