Followerwonk - Followerwonk by Moz is a Twitter analytics tool to help companies better understand their Twitter followers.
SocialRank - Graph search for TWTR. Filter by interests, location, etc
Twitonomy - Twitter analytics and much more.
Flock - A faster way for your team to communicate
Accountanalysis - A tool to evaluate Twitter accounts
FollowerAudit - FollowerAudit is a platform that allows users to check their fake followers and track the follower growth of any Twitter Account.