http://www.tweetfriends.com/ 

How can you use Tweet Friends? Find out who you may want to follow by looking up mutual friends of two people you love to listen to or Find out why a new follower has added you, and if you have any Twitter friends in common. 

Ok so if you want to use tweet friends you need to understand what twitter is in the firs place. Well its a lot of things. 

First it thinks its just an instant messaging service or a micro blog. But it is really much more.

It is a branding application, You can use it to find a job, keep your employees up to date, Keep your self up to date, get news , Find Prospects, Provide live coverage of and event. Get product idea and feedback.

I have only scratched the surface of what it can do. But to do most of this you need to have an audience or you need to follow people. Thats why you need www.tweetfriends.com