What are your favorite work out songs?

I had this MP3 Player that had all of my workout songs on it. Well, i don't have it any more or the computer that had the songs on it. So i'm starting from scratch. I was wondering what were other peoples favorite songs to work out to. I personally like up beat pop like Fergie and Britney. But I also like to listen to punk rock and stuff that gets me riled up.