Whack Tweeple Who Don't Reciprocate

Unfollowing tweeps not following you is really wicked and a rude thing to do, but if you are looking for a client that has its features then Twiiter Karma is just the right Twitter app for you.

Twiiter Karma is a Flash application that fetches your friends and followers from Twitter when you click the “Whack!” button, then displays them for you, letting you quickly paginate through them. By default, the list contains all your friends and followers and is sorted by last update, showing those who most recently updated first. You can sort the list alphabetically either ascending or descending by Twitter ID. You can filter the list in several ways: only friends or only followers, all friends or all followers, and mutual friends.

See the buttons?

Like I said, reciprocating is a virtue. :)