Have I ever raved about NationStates? I suspect not, but my memory is getting rather shoddy. I learned about it some years back from ICJ, and I've periodically returned for brief spells of addiction.
Basically, you set up the style of country you want, answer a few questions to give your thoughts on various social issues, and away you go. Twice a day (or less, if you prefer) you get new issues, and your rulings will gradually affect things like tax rates, civil liberties, the environment, and so on.
It's a real kick, though as I recall it has a brief play-period -- the questions start repeating themselves eventually, though maybe they've added a lot more. In any case, it always makes me laugh, and I've just started again. So come on by and say hi -- at Kloucekvania!