Just got the topic icon plugin up and running. I'm using it for an extremely frivolous use: I wanted to have a little colored box next to 'Posted,' and I needed some mechanism for making it different colors for different posts.

This plugin was a little harder to install than the others b/c the documentation neglected to mention that you need to embed it in a MTEntryCategories tag (or, at least, I could not get it working until I did it this way).