Pigi

With Digg Links you will be able to replace a word or sentence into another custom string.
For example every time you write CJ (or cj, or Cj, or cJ) Digg Links will turn the word into Commission Junction or 
<a href="http://www.cj.com" rel="nofollow ugc">Commission Junction</a>.
Based on Link a Dink this plugin is ideal for affiliate marketing.

Digg Links

With Digg Links you will be able to replace a word or sentence into another custom string.

Thomas Schulte

This plugin dynamically shows preview screenshots of hyperlinks as tooltips on your WordPress site.
For the tooltip effect a jQuery plugin called “qTip2” is used internally. 
Find more about this great project here: http://qtip2.com/ 
The thumbnails are provided by http://thumbsniper.com and its API.

ThumbSniper

This plugin dynamically shows preview screenshots of hyperlinks as tooltips on your WordPress site.

Digg Links vs ThumbSniper