Go to tinyurl.com. It's a wonderful idea - you get a simple, quick service that converts very long URLs into very short ones.
For example, one of my permalinks got converted into a very short URL which looks like this: http://tinyurl.com/45z4e
Update: Thanks to Jesse, who pointed out the ASP.NET version: http://shrinkster.com . My permalink is now also: http://shrinkster.com/3o6. I am also able to track the usage of this URL from here: http://shrinkster.com/Track.aspx?AddressID=3o6