Times are tough, and lots of folks are carrying around pent-up aggression. Give them a chance to vent (while giving something to the needy) by holding a car bashing event. For the price of admission, mild mannered citizens can whack the dickens out of a car. Charge a few dollars for privilege. This requires some planning with safety in mind, and includes getting the proper permits, providing protective gear, and keeping crowds well back. You should also have someone trained in first aid standing by. The nice thing is that you may be able to get a local junkyard to donate the vehicle for the cost of transporting it. Just make sure the tanks have been drained and any hazardous materials have been removed. Check with your local fire department for tips and suggestions.
This event dovetails nicely with police, emergency services and fire department presentations, too, so be sure to check around to see what types of shows and other exhibits you may be able to add to the fun. Oh, and if you're using a sizeable location with street access, hold a car wash at the same time. It will help attract street traffic to your event and earn extra revenue.