ThemeShock

This lightweight plugin creates a form that is placed by default at the left of the 
content, and is fixed to the top of the page once it gets to it.
Floatin Comments serves as an alternative form to post comments that is very handy 
compared to the traditional comments form. Given that it follows you as you scroll down by 
the page, you can post a comment being at the bottom of the page but also at the 
top.
This plugin is available in 5 different languages, English, Spanish, Portuguese, 
French and Dutch, it will recognize your WordPress installation language and if 
yours is in one of the previews languages you’ll have it automatically 
translated.
<a href='http://www.wpthemeshock.com/' rel="nofollow ugc">By WpThemeShock</a> and <a href='http://www.wpthemegenerator.com/' rel="nofollow ugc"> WpThemeGenerator</a>, <a href='http://www.designshock.com/psd-text-styles/' rel="nofollow ugc">see it in action.</a>
<h3>Features</h3>
<ol>
<li>4 Different Colors</li>
<li>Fixed position when the form gets to the top</li>
<li>Ajax-Powered</li>
<li>Get 100 free sample WordPress Themes</li>
<li>5 Different languages, English, Spanish, Portuguese, French and Dutch.</li>
</ol>

Floating Comments Form Fixed Scroll Position

Floating Comments allows users to post comments to your blog through a fancy form that fallows them as they scroll down.

chatWING

ChatWing is the ultimate free live chat service, instantly chat from any device. 
ChatWing is 100% cloud based live chat, talk on websites, via direct links like “chatwing.com/Mygroup” and inside this app. 
Instantly create new rooms, invite users, put any chat room directly on your website or blog and connect to the app. Also use ChatWing as a direct live chat messenger with friends, contacts or to meet new people.
<ul>
<li>Create unlimited chat rooms with unlimited users.</li>
<li>Choose to login with numerous social accounts including, Google, Facebook, Instagram, Twitter, Tumblr, Yahoo, Vkontacte, ChatWing and more.</li>
<li>Use the lobby feature to join any existing room.</li>
<li>Search for specific rooms you usually chat in on websites and blogs, take that room on the go once bookmarked.</li>
<li>Bookmark unlimited chats and have instant access anytime.</li>
<li>Many customization controls allow the ability to edit your text, fonts, insert video and images direct and much more.</li>
<li>Connect your room to the Chatwing Android and IOS (ipad/ipad) apps</li>
<li>Receive alerts and notifications of new messages via chatwing mobile apps</li>
<li>Embed Chatwing into any webpage both Javascript and Iframe HTML code are available for each room</li>
</ul>

Plugin Name: Chatwing Float Chatbox

Chatwing offers an unlimited live website/blog chat experience.This chat widget specializes in delivering real-time communication at any given time

Floating Comments Form Fixed Scroll Position vs Plugin Name: Chatwing Float Chatbox