huitter is a nice twapp which helps you in unfollowing all those people on twitter, who don’t follow you back.
huitter just demands your twitter user name and password, and automatically removes “not following back” users from your account in seconds.
FriendOrFollow is another twapp to check and manage your twitter friends and followers. Following many people on twitter helps you in spreading & getting information easily. If you hate to having too many friends on twitter, you should check twalala. using twalala you can mute selected friends on twitter. Hence, you can avoid their updates and can use twitter effectively.
Link : huitter.com
Update: huitter seems to be dead now! :(