URL shortening services were initially popular because web addresses started to get long and links would break when sent in an email. However, as microblogging services like Twitter have become popular, an increasing number of services and applications, including tracking & metrics, have been added to the basic URL shortening features.
View list of programs here
http://www.toprankblog.com/2009/01/11-best-url-shortening-services-vote-your-favorite
