Ultimate Category Excluder is a WordPress plugin that allows you to quickly and easily exclude categories from your front page, archives, and feeds. Just select which categories you want to be excluded, and UCE does all the work for you!
TechTags is a simple Technorati tags plugin for WordPress. Add a single line to a post or page to display Technorati tags.
Multi Column Link List generates an alphabetical listing of your WordPress links in multiple columns. You can choose the number of columns to display, with an option to split up the list of links by letter.
Cimy Page Navigator generates page lists which can be styled with CSS to create navigation menus.