Costume Ideas?

Well it's that time of year...the ever-controversial Haloween! We have been invited to a costume party and I love dressing up! I always have! (My favorite gift as a kid was my aunt's old prom dresses and costumes she wore in plays!)
Now, the controversy aside, I need ideas for a costume! :) Are you dressing up? Are you dressing your kids up?

My schedule of events for Friday evening goes as follows:

6-8 PM ish Trunk n Treat at SMIC

Last SMCS home football game

Costume party at Jeremy's

So, I need a costume that is multi-function and warm!
Scott, by the way, is going either as a College Pastor, or a Church Administrator. Not imaginative...
Oh, and if you have kids, bring them by the Trunk n Treat! We will have not just candy, but food (hot dogs and such) and bouncy things for kids to play in.