currently running a costume contest rewarding people who dress up as characters from one of the 600+ films in the Criterion Collection. This sounds like a daunting task, since it's hard to pull of a recognizable Antoine Doinel costume, but Criterion's archives are full of exciting and costume-able characters. This is Spinal Tap, Brazil, and Armageddon, for instance, both saw Criterion releases.
If you send Criterion a picture if your costume by the end of the day on Halloween, you'll be entered to win a Criterion-themed gift bag. No telling what's inside except winning!
Wikipedia has a handy list of all the films released by Criterion if you need a reference.