John at Area 42 has created a new Movable Type Plugin that allows you to associate icons with categories. This plugin is used on this site, as you can see. Download it here. All you need to do is modify the topicon.pl file and then upload it to your “plugins” directory in your MT directory. Because Apache servers already have an “icons” directory created, this seems to play havoc with them, giving you broken images, I solved the problem for my own installation by naming my icon directory “topicons” (which is what it should be named to begin with, I think). Once I did that, everything worked perfectly.