Tupac, Kanye and Elton, Together Forever

Ever hear a new song - say, Flo Rida's latest stripper anthem "Right Round" - and swear it sounds familiar? There's a reason why: A good chunk of the music today actually uses a sample, or a snippet of a previously done song. "Right Round" might be kind of obvious, as it apes Dead Or Alive's '80s camp classic "You Spin Me Round", but other songs hide their samples well. Radio sounds the same today because, well, a lot of it is based on the same songs as yesterday.

Who Sampled is a fun site that tracks down which songs are based on what. For instance, Depeche Mode's Personal Jesus has been sampled at least twice - including last year by Hilary Duff. (Um, what?). Sir Elton John is actually a favorite among the hip-hop set, as he's been sampled by both Tupac Shakur and Kanye West. Who knew?

Who Sampled is an active community, so if you hear a song and you know the original it sampled from, you can upload the before and after yourself.

(Image courtesy of Getty)