mine are mainly car based forums..

wiltshire bikers - obviously the best forum online!
talk-torque - my main car-based forum
triumphrat - use it for triumph info now and then
206info - great forum for 206 drivers (like me!)
206cc owners club - as above, but very very quiet - one post a week if you're lucky
peugeot gti autosport club - had enough of this club now, been there for 5 years but it's gone down the pan
performance car club - dying a death so soon to be taken down
205gtidrivers - excellent forum but VERY strict
southwestbikers - good for a read sometimes

mainly just use the 2 forums though, this one and talk-torque. the others are for a couple visits a week when I'm bored!