onrpg - to use the chatbox/out of habit, because I feel mostly at ease here
somethingawful - to lurk and read let's play threads, the paradox thread, and the grognard games thread... when the paywall isn't up, anyway.
electricalaudio - to lurk and read about music mostly, also films and stuff
questionablecontent - shitty comic, used to be a good forum, less so since all the best users evacuated. music, films, comics. I was only an occasional poster.
giantbomb - when I'm bored. kinda shitty forum, though with the occasional useful nugget of information