TweepDiff -Allows comparing followers associated with Twitter accounts Tweepdiff.com

1. Enter 2 or more Twitter usernames (e.g., our Twitter username or screen name is  "tltgroup", usually mentioned or referenced within a Tweet as "@tltgroup"; similarly, Derek Bruff uses @derekbruff as one of his Twitter usernames/screen names)
2. Indicate for each username whether you want to compare the associated list of usernames who are FOLLOWING that one or the list of usernames who are being FOLLOWED BY that one
3. Press the "Compare" button
4. Get a count and a list of usernames common to all you have entered.  

"TweepDiff is a tool that allows you to compare the friends or followers of two or more Twitter users to see who they have in common. For example, a common use for TweepDiff is to compare your own friends and followers to see who you follow that doesn't follow you back or vice versa. Another use is to compare who you follow with someone else to see if they know of people that may be interesting to you."
- above excerpt from http://tweepdiff.com/about

Why?
"If you think someone else is a good judge of Twitter usefulness, you can diff yourself with them to discover new people to follow."
"By entering your name in both boxes and choosing friends for the first box and followers for the second, you can see who is following you, that you aren't following back, or who you are following that isn't following you back. This may help remind you to follow people, or it may remind you to unfollow someone who is no longer following you."
- above excerpt from http://signalsready.com/products/tweepdiff/

IMAGE

Photo of "Die Zwitscher-Maschine (Twittering Machine);  Watercolor and ink; oil transfer on paper with gouache and ink borders on cardboard. Group of birds shackled to a wire attached to a hand crank." Date 1922;  Image hosted at <http://www.waggish.org/2010/paul-klee-twittering-machine/> by Paul Klee

http://upload.wikimedia.org/wikipedia/commons/thumb/0/09/Die_Zwitscher-Maschine_%28Twittering_Machine%29.jpg/500px-Die_Zwitscher-Maschine_%28Twittering_Machine%29.jpg

http://upload.wikimedia.org/wikipedia/commons/0/09/Die_Zwitscher-Maschine_%28Twittering_Machine%29.jpg

Permission  "This work is in the public domain in those countries with a copyright term of life of the author plus 70 years or fewer. 

By Paul Klee [Public domain or Public domain], via Wikimedia Commons

TweepDiff - Find Out Who You're Missing On Twitter