2. Googler
Google has become just about as famous for its (allegedly) happy-go-lucky employee culture as it has for, well, revolutionizing a whole lot of stuff on the Internet. So much, in fact, that any well-informed audience could probably tell exactly what you were if you chose to dress up as a Googler for Halloween.
Wear jeans with bright, primary-colored sneakers and a Google T-shirt. Don't have one? Try the Google Store. For a hat, wear a striped beanie with a propeller on top. If you can find a Razor scooter somewhere, that's a must, since Googlers really do ride them around the office--and you can hang your pumpkin-shaped candy tote from the handlebars.
If you'd like to be really insidery, drape a cuddly toy snake around your neck. Remember Kaiser?
Photo by Maggie Reardon/CNET News.com