A list of some useful tools for managing your twitter accounts.
they have been divided into two categories:
1) follower management
2) analytics

1) follower management
wefollow.com – fill in your details so that others can follow you
untweeps.com can use 3 times a month to unfollow stale peoples
tweepi.com – loads of things: find cool people to follow.
twitblock.org – scan twitter following for spammers so you can remove them