urlBorg is a "URL-shortening" service built on Google AppEngine for scalability. Users can login using their GMail account to set their preferences and enable history.
urlBorg provides stats for each short link and enhanced "preview" pages that display additional information depending on the link type (ex. an embedded audio player for links to mp3 files, etc.)
Site owners can set their own "short domain" that will be used for all short links pointing to their site.