For those out that don't visit the library too often, I wanted to let you know that you can check out Museum Passes. You check them out for a week and they usually allow 4 general admissions for free. Not all passes are available at all times, but give it a try.
The options are Brookfield Zoo, Science & Industry, Field Museum, Shedd Aquariam, Nobart Nature, and a few others I can't think of right now. In these tough economic times, enjoy a day out for practically no cost.