Usenet is not too bad, if you don't mind digging through spam.
Very little spam in the game groups - the ones that start out ibm.sys.pc.games.***. The digital SLR group I frequent gets no spam as far as I know. OH - WAIT - you mean spam resulting from using usenet. Easy - just put a fake e'mail address in both the reply to and e'mail address fields in the account setup of whatever news reader program you use. Spammers can't mine what isn't there.
If I'm in a really pissy mood I'll occasionally drop by one of the numerous alt.religion.* or alt.politics.* groups and drop the ole trolling lure in the water. That can be a real hoot.
Try going to a hardcore religion newsgroup and start a thread about evolution, or complain that GOD must be a real psycho to have had his own son tortured to death - that's always good for a few laughs.
On the politics groups it is a little harder to start a good troll as the average IQ level seems to be about 40 or so points higher than one finds on the religion groups.
Its all FUN FUN FUN... it is just so easy to spin people up and watch the resulting spatter - hell - it ain't that hard to spin me up - maybe that's why I like trolling usenet.
Mostly though I've not found any internet forum be it usenet or web based more civilized than THR or APS. 99% of my postings are on THR or here. AND though I'm sure some on THR and here imagine me to be quite aggressive, opinionated and maybe even a bit whacked - compared to the usenet norm I'm a fluffy baby kitty.