Sports leagues are always fun.... You could maybe get 2 friends together (just so you don't have to go alone) and sign up for co-ed volleyball or something.
Lots of cities have programs that are specifically geared toward twenty-somethings. They have the games early, then everyone goes to the bar together where there are specials set up. Fun times!!!!
Also, I don't know if your alma mater has a big population where you live now... But I met a ton of people my age by going to Happy Hours hosted by my local A&M club.
Book clubs could be fun, but you might not be as likely to meet women your age.
I'm kind of in the same situation as you, so if I think of anything else, I'll let you know.
