Grooveshark is a free online jukebox service. Users can search for tracks and listen to them right inside of a Web-based player. Similar to software jukebox applications, users of Grooveshark can control music tracks as if they were playing them right off a hard drive. It also lets you save and create playlists, and mark songs as favorites.
Grooveshark has two companion applications, a widget creator for sticking the GrooveShark player on blogs and social networking profiles, and a link shortening service for use on microblogging services like Twitter.