One of WordPress’s greatest features is that its capabilities can be expanded by the use of “literally hundreds of plugins”. A list of my currently active plugins can be viewed here.
At this time, there are three ways to find WordPress plugins. The first would be to visit the official documentation on Plugins. The second would be to visit the Unofficial WordPress Plugins Database. And, the third would be to visit the Official WordPress Plugin Repository. If you are having trouble downloading plugins from the Official Repository (a user-friendly version is on the way), you may want to try Red Alt’s WP-Plugins Download Interface.