Bolla-Url-Shortener is a project mainly written in ..., it's free.
Asp.net MVC3 Url Shortener
An ASP.NET MVC3 application that creates shortened URLs
I was working on a site one night that needed a URL Shortener. I had not really seen anything out there that I could plug into my own sites, so I thought I would make one. A couple hours later I have a URL Shortener that does the trick. I need to spend some more time on it to clean it up. But I like what I have so far.