If you're the competitive type, http://codeforces.com http://codeforces.com is also very good. You get an elo rating and they use chess titles (candidate master

If you're the competitive type, http://codeforces.com http://codeforces.com is also very good. You get an elo rating and they use chess titles (candidate master, master, grandmasters, etc). The lower division generally has around 20k participants per contest which mostly (but not always) happens on weekends.