You might have heard of Travian. If you heard of tribal wars, you've heard of it. You probably think Travian is boring, but the 3x one goes VERY fast. speed.travian.com
The next one is Kingdom of Loathing. It's a unique stick figure game where a ton of people play. You level up, fight bosses and stuff, then you can restart with more skills.
www.kingdomofloathing.com
The one im playing now which is quite fun is OfficeDebo. You basically have the usual professions. Fishing, Smithing, Mining, Pickpocketing, Battling, and Farming and you just level them up and you get rich in the game, but the community there is very nice, very laid back members and quite fun.
www.officedebo.com
Oh yeah, and if you want to play online risk, try conquerclub. Many players like to play RT (Real-Time), meaning they keep playing by the minute until the game is over or until someone has to go, but even if people do not play RT, they have 24 hours to make a turn, until it goes to the next person (unless it's freestyle where everyone makes the turn at practically the same time). Anyway, to catch on to the interface it is not hard at all, i got it in within like a game or two.
www.conquerclub.com
Hope that helps, chrono