The best costumes are the ones you make. Over the last few years, I've been DuffMan (from The Simpsons) and Stewie (from Family Guy). A few good ideas that will make a good impression are Beaker (from The Muppets) or one of the paper bags from the Fandango commercial. It'll take some creativity (or looking them up on Google).

Pirates are huge this year.. I can't believe how much I am seeing.. also sexy wenches.. there is no one character that's rocking the world.. other than maybe a penguin.. but that's sort of hard to dig up a penquin costume. hence the Pirates thing (a la caribbean) .. I would also look at Disney for the Pooh things and also usual suspects in that genre

How about you dress up like one of your fav band/singer/actor? That would be fun..

MASTER CHIEF from Halo series! Or the ever popular Storm Trooper!