Have a favorite place you like to go? The Zoo, the Aquarium, a Museum? Check into getting a membership. They are usually fairly inexpensive (less than 100 dollars usually). You get the benefit of free admission (you can figure out how many times you have to go before you pay for your membership...) as well as other benefits (discounts at their store, reciprocity with other museums/zoos/aquariums). Your membership dollars are also going to help out an organization that is using the money to put toward educating the public. Do some good for your community (and your wallet) and buy a membership.
I got a membership to the zoo here in Norfolk and we get free admission to the Baltimore Zoo when we go up to Maryland to visit. Awesome deal!