F&NI: The simple questionnaire-based stuff, yes. Previously I had an embassy thread.
NationStates: Pretty much never apart from one space RP group.
II: Nope, too time-consuming to make a good RP post.
GE&T: Sometimes I lodge an order in a storefront that interests me. I also had an airport storefront that I left to rot twice.
NS Sports: Pretty much never.
GA: Sometimes, to report an illegal proposal or to comment on an interesting (or particularly bad) proposal. I also maintain the list of GA committees.
(Update: I wrote 532 GA "International Radio Standards Act".)
SC: Pretty much never, since I'm strongly anti-SC and anti-R/D.
Gameplay: See above.
Got Issues: Only to report what I think are mistakes in issues.
Technical: I read and post here quite often these days, and I have made two API tools too.
Moderation: Not much except to report spam, adbots and the like.
General: Avoid like hell.
Arts and Fiction: Not an arty person, so no.
P2TM: Yes, for the NS Parliament.
Forum 7: Yes, mainly for the AN's flag and AN's sig games.
Cards: Nope. These days it needs a huge number of puppets to be relevant in cards.