Definitely a mix, but my class likes remixes a lot.
Their favorites are:
I Gotta Feeling (Black Eyed Peas)
Karmastition (Mash up by Go Home Productions)
Beautiful Dangerous (Slash featuring Fergie)
Knock this Way (Mash up of Lady Gaga and Amii Stewart)
Most songs by The Killers
Everybody Got Their Something (Nikki Costa)