StumbleUpon the web site discovery service has opened its URL shortening service “Su.pr,” similar to TinyURL, Snipr,  Bit.ly etc., it lets you shorten a long URL into just a few characters to share in an email, Twitter message, Facebook status update etc. Su.pr also offers a analytics to let you know how many times users have clicked on your links. And every time you shorten a link, you also add a web-based StumbleUpon toolbar to the link that lets users vote on the story. In other words, when you shorten a link through Su.pr, you're not only able to share it with friends & readers, but if they like it they can vote it up to bring StumbleUpon visitors to your site.