One way to celebrate Halloween is to dress up like a city. This costume could rely heavily on stereotypes, but can also be influenced by current affairs. For example, get yourself a black eye and put your arm in a sling, and bam, you're Detroit. Or block some traffic and set up lawn chairs on a local street and you're New York City. Or you could get Brad Pitt to follow you around and be New Orleans' Lower Ninth Ward.
This may be the most relevant costume idea this year. Just get some cardboard and build yourself inside four walls and a roof – and don't forget to board up you doors and windows. For added effect, go with a group of people in foreclosed home costumes and some dark eye makeup and you're a zombie subdivision. Scary!