How to find out if someone is following you back on Twitter

I was trying to determine if one of my colleagues was following me back on Twitter and ran across Doesfollow.com.  Doesfollow offers a very simple interface that allows you to add Twitter handles to answer the question: Does _______ follow _____ ?

You just enter the twitter handles to get results like this:

There’s also a “funny” option for humorous and sarcastic responses.  This simple tool could be very helpful if you are looking into any Twitter user’s connections.

I have gotten over Lady Gaga not following me back.  The President, @barackobama, does.