Things to do in Atlanta, Ga?

Travel Info
I've lived in Atlanta for about 5 years. I've been dating my boyfriend for about a year and 1/2. We don't really get out too much. What are some affordable things to do in or near Atlanta. We've been to Helen, Ga, Blue ridge, Stone mountain, six flags, but other than that we pretty much just go out to eat. We are bored.
Thanks :)

Travel Tips

You should check out FDR's Little White House in Warm Springs. It's only an hour or so south of Atlanta. Inexpensive and very historic.

Sweetwater Springs State Park (near Six Flags) is a great place to go for a day-hike. It's cheap -- just pay a nominal parking fee.
Others

Just got back a couple of weeks ago from an anniversary trip. My husband and I really enjoyed the Georgia Aquarium, the Botanical Gardens, Centennial Olympic Park, our tour of CNN...and even though I don't like baseball I really LOVED watching the Braves at Turner Field. It didn't hurt that they won LOL.
Coca-Cola World
Six Flags Over Georgia