I know there are literally thousands but I was intrigued and began working on mine. http://neap.us. It doesn't have a design because I'm busy working on the backend but after I get done, it will have stats tracking, user accounts, custom urls and much more. It's currently coded in PHP but I may possibly end up recoding it in Ruby. Please try your worst at breaking it and tell me what happened. I do need some beta testers.
Now we've got custom URLS working, also have an API but no one has contacted me who could be interested in using the API. http://neap.us still doing backend work so design will have to wait. EDIT: Our stats page is located @ http://neap.us/stats
Does this gives value when it comes to Search Engines? I'm wondering using 301 redirect for effective results.