i really like the north and south idea that rebelsweetheart mentioned, and the cops and robbers idea! one of my best friends is our new social so now i can give her good ideas.
some of our mixers have been..
-golf pro - tennis hoe
-grafitti party
-hell's angels (guys dress as devils, girls as angels)
-80s theme
-cowboys/cowgirls
-school girl
-i dont think this one had a name, but we were tied at the wrist to a guy all night (going to the bathroom and all.. it was interesting)
..we've had a bunch more but i can't remember all of them now!