B&B
Shavemyface
cloudy nights
ride on two
Ubuntu forums

i have signed up for others but i am always on here and ride on two (especially during race season). B&B is good but i only go on when i have DE questions, i don't spend much time on ShaveMyFace. Cloudy Nights is a great Telescope forum though i am not on it as much anymore. the Ubuntu forums are essential if you run Linux.