- Top Categories 1.0 - for version of wordpress 2.0+ (updated 01 Mar 2006)
I created a new wordpress plugin called Top Categories. You tell it how many of your most frequently posted to categories you want it to show and it will display an unordered list of those categories. It is based off of the Popular Tags plugin by Theron Parlin which was based on the weighted categories plugin by Matt Kingston. Unlike either of those plugins I do not display a tag cloud - but that might be a good option so that this one plugin is a bit more flexible.
You can get this plugin downloading this zip file. Usage is pretty simple:
<?php top_categories(10); ?>
You can replace 10 with any positive number you want. By default top_categories() will show the top ten categories. This plugin may work with wordpress versions before 2.0 - but I haven't tested it.