What are some 18th birthday ideas?

I will be 18 in less than two months and was trying to come up with some birthday ideas. I know I do not want a big party or anything like that, but I would like to do something fun and cheap, but I cannot think of anything. i thought about doing something in Atlanta since its not too far, but i couldn't find anything to do there that would not cost a lot. Any ideas would be great!