Comment Info Tip is a WordPress plugin that provides you and your commenter’s a bit of information on their posting stats. When you mouseover a commenter’s name you will see a tip appear displaying some information about that given commenter. The tip will display 1 of 4 results:

• If the commenter has only posted once then it will say so in the tip (see number 1 in the legend below).
• If the commenter has posted more than once we will look up the last three posts they have commented in and display links to those posts. This allows you to see which type of posts this user is interested in and easily navigate to those posts (see number 2 in the legend below).
• If the commenter has posted more than once we will attempt to search their RSS feed and show an excerpt from their last post (see number 3 in the legend below).
• If it’s a pingback or trackback the tip will indicate so (see number 4 in the legend below).

Pricing: Free
Requirements: -
Source: http://www.search-this.com/2008/05/05/wordpress-plugin-comment-info-tip/