Sitcoms vs. Dramas? TV vs. film? Models vs. Actresses (or musicians vs. either)? Various historical showdowns (hottest girls of the 60's, 70's, etc., set in the appropriate era)? The possibilities are endless. For some of these it might be interesting to take nominations, though if I was you I wouldn't be bound by them. Above all, use ideas that interest you, so you are invested enough in the idea to see a tournament through. Best of luck!
-JM