CantonBolo

Features: 
1. In addition to the jQuery library, only need to load some little JS files and some little of CSS files. 
2. The output code of the plug-in on the page in line with W3C’s XHTML 1.1 and CSS 3 standards, and the code structure is very simple. 
3. When deactivated，the images calling code generated by the plug-in will not cause any adverse effects.
This plugin allows you easily to make <a href="http://flowplayer.org/tools/demos/overlay/gallery.html" rel="nofollow ugc">Overlay gallery</a> popups on WordPress.
这个插件助你在 WordPress 中轻易地使用 <a href="http://flowplayer.org/tools/demos/overlay/gallery.html" rel="nofollow ugc">Overlay gallery</a> 相册功能。
<h4>Supported Languages:</h4>
<ul>
<li>US English/en_US (default)</li>
<li>简体中文/zh_CN (translate by <a href="http://imbolo.com/" rel="nofollow ugc">bolo</a>)</li>
</ul>

Overlay4WP

Easy to use Overlay popus gallery in WordPress.Base on jQuery Library.

AbroadPal

Notification Widget offers you the ability to insert and fully customize an overlay widget for your website, blog, etc.
You can easily change all settings of the entire overlay in the Dashboard. 
There are the following settings for you to change:
Overlay Style: 
– colors of bar and content frame background 
– text of the content frame and bar
Overlay Layout: 
– distance of the close button to the borders 
– size of the close button 
– height of the bar 
– height and width of the content frame 
– widget position (X- and Y-axis)

Notification Widget

Notification Widget is a overlay allowing you to get a individual overlay for your website.

Overlay4WP vs Notification Widget