Neat Homebrew Halloween Tech?

aibrahim asks: "I just saw a proton pack (alternate site) a friend has built. It made me wonder what other neat high tech things the Slashdot crowd might be brewing up for the coming holidays. What I am really after is stuff that one of you made, better yet would be diagrams or explanations of how you made it. Doesn't have to be a costume item, anything interesting that fits the season would do." This is a follow-up to the earlier article. So what are you dressing up as for Halloween, and how do you plan on making your costume interesting?