tr.im makes the shortest short-urls ever by virtue of the short address, and also the widget is amazingly useful. You don't even have to copy the URL and paste it in, it gets it automatically from whatever web page you're looking at! Kool.
And you don't have to select and copy it either. Just one click. I like that. I'd like more engineers to think like that. Save clicks. It's only recently that youtube has the cursor already in the searchfield when I arrive. And Amazon still doesn't.