I found this website that helps you find fun things to do in some cities on the cheap.
It does not contain cities in all 50 US states, but does have some Hawaii & Toronto ideas...for the young at heart there is some Disney on the cheap stuff too. Check it out they may list a city near you.
If you live in NYC there is a good PBS NYCTV show called $9.99. They have some good ideas on things to do in the city for a train pass and you guess it $9.99 in your pocket.
Until next time, when we can chit-chat again!