The Escapist
Came here for Zero Punctuation, stayed for the forums - I can access at work so it's always open on one of my monitors.
Zombie Pandemic
As above. I can access it from work and it doesn't eat up bandwidth indiscreetly. Keep an eye out for BillySunset if you play!
4chan
Usually /tg/ and /x/ for my geek and horror fix - I'm a 40K afficionado, and love when people start arguing about what would happen if the Emperor reincarnates or becomes an actual God or just simply dies. Some of the ghost stories on /x/ are great, and the nutjob doomsday prophesies are always uplifting. And then there's /b/ ... which is like Chaos Undivided and you can't hang around there without being ... changed. Perhaps 'sullied' is a better word.
Used to be a regular at Spiked Humor before it closed down though ...