If you happen to be a Bank of America cardholder, you can get in FREE! to many zoos, botanical gardens and museums across the country.
P.S. I do not endorse owning a credit card just for the sole purpose of getting into museums for free. Especially if the plan backfires, and enables you to live any which way but providently. I don't happen to own one of those, but I might find a friend who does!