Vincent Mimoun-Prat

This plugin allows you to get better control on how your categories are listed. It provides a widget which lets you get more options than the default WordPress category widget (show RSS, hide empty categories, etc.). Furthermore, it allows to hide the children categories and use clickable buttons to expand them. The plugin requires jQuery to be included in your theme. It degrades nicely when javascript is not available to the usual WordPress category list.
All the instructions for installation, the support forums, a FAQ, etc. can be found on the <a href="http://enhanced-categories.vincentprat.info" rel="nofollow ugc">plugin home page</a>.
This plugin is available under the GPL license, which means that it’s free. If you use it for a commercial web site, if you appreciate my efforts or if you want to encourage me to develop and maintain it, please consider making a donation using Paypal, a secured payment solution. You just need to click the button on the <a href="http://enhanced-categories.vincentprat.info" rel="nofollow ugc">plugin home page</a> and follow the instructions.

Enhanced Categories

A plugin for wordpress which allows you to list your categories in a sexier way. Very useful when you have a great number of categories.

A big cloud of all your blog’s tags is cool and all, but I thought it might be 
fun to try to integrate tags into the whole navigation scheme. Altocumulus will place a cloud of related tags at the top of your Category and Tag pages.
If people are interested and I have the time I’ll try adding more 
functionality. Thanks for trying it out.
You can see a sample <a href="http://www.unsoughtinput.com/index.php/tag/the-internet/" rel="nofollow ugc">on the internet</a>.

Altocumulus

Altocumulus places clouds of related tags on your Archive pages.

Enhanced Categories vs Altocumulus