There are lots of neat sites to help you familiarize yourself with, and build, your Twitter community.
Here are a couple that come to mind:
Twellow — White Pages for Twitter
Qwitter — Site that lets you know whenever someone stops following you. The site seems to pride itself on “Catching Twitter quitters.” Sneaky!
Search.twitter.com — A Twitter search engine
Twittersheep — Characterizes your “flock” of followers using keywords
I experimented with Twittersheep and found that words such as “journalist,” “media” and “reporter” best describe my Twitter followers. No surprise there! You can find me on Twitter @mallarytenore.