Image by Flickr user TMeyer88
In an article aptly titled "Free Charleston!," Sarah Langdon has compiled a load of tips on how you can enjoy your time in the Holy City without breaking your bank (unfortunately there's no escaping the price of gas, parking, and lodging.)
Not only does Langdon do a swell job of compiling good sites to see, but she links to more information about them. Nice.
Bonus points: New York Times' guide to Charleston on the cheap from two years back.