I made this plugin because of a request in the b2evolution forums, but I've been wanting something like this for myself for a while, too. It adds a box in your sidebar listing the posts with the most comments. The number of posts to list can be set to anything, but the default is 5. You can get the plugin here, but I also ported this back to the current stable version of b2evolution: 0.9.1, so you can see it in action in my sidebar (scroll down to the bottom of the sidebar). If any other Brendoman.com authors want this added to their skin, just let me know.