Tr.im shortens and tweets URLs, tracks stats, and more
Tr.im does just that. Apart from offering URLs that are about as short as you're going to get (8 characters on my tests), they've added a couple interesting features.
For starters, Tr.im will truncate your link and automatically update your Twitter or Identi.ca status. The service also tracks stats and allows commenting on your URLs. There is, of course, a bookmarklet and API access is provided for developers.
Creating an account allows you to store your history and gives you access to a number of useful preference settings. Tr.im doesn't even require creating a new account to log in - just use your Twitter credentials.
You can choose to auto-copy new URLs to the clipboard, automatically trim and tweet, and save your Twitter and Identi.ca passwords. Another interesting feature is Tr.im's retweet service, which automatically adds popular submissions to their Twitter feeds.
It's an excellent service, and may just be my new favorite truncator.