Carissa Knits has a great free pattern for making a hip R2D2 beanie, complete with little wooly monocle turret:
Want a handmade Halloween costume this year? Have a geeky friend whose birthday is right around the corner? Or perhaps you are that geeky friend. That's okay. Be proud of who you are. Shout it out loud without saying a word. Knit this hat and wear it everyday, everywhere.