where those interested in historic motor racing gather.

Also Photo Net, where people argue about cameras.

I contribute to the excellent Adrain's Album Reviews and host my own Classic Albums Podcast blog - very lively.

Also a member of that forum, although I am only a very occasional poster. It kept me sane during the last World Cup when the national team became a laughing stock.
Used to post on a Danny Baker forum until it got too argumentative and cliquey.

Plenty of discussions about American politics, humour, photography, aviation, live music & records.

Very little about the subject matter in the title. Greg Lake. Gone AWOL.

Have posted on smurphy's Classic album but other than that no. Work gets in the way and I genuinely think the Word website (and its bloggers) is more interesting than any other site by miles.

I contribute regularly to fieldhockeyforum.com which is, unsurprisingly, a forum for (field) hockey discussion. You wouldn't believe how much anger can be generated from discussions about the rules and other aspects of a minority sport...

and about a million blogs

I read daily and post occasionally on scfc.co.uk (a Swansea City football site's) message board. It's need to return is based upon two regular posters (who happen to be father and son) who continually disagree on every conceivable issue. Any thought that this was for effect was destroyed when I saw them physically being pulled apart during the playoff final defeat in 2006. We lost the game as well, on penalties, must have been an eventful journey home in the car for those two that night.

then they would have killed each other I'd expect

in the alt.usage.english newsgroup. I still nip back occasionally but it's not what it was, or perhaps this blog is what I was hoping it would one day be but never quite managed. I do keep up with about half a dozen other blogs but apart from the odd hit-and-run comment (hi, Mr H! Hi, Rob!) this is the only one I contribute to regularly.

Perhaps online communities are like your local - once you've plumped for one, it tends to be your default destination.

Fairport and beyond, although I tend to spend most of my time in 'The Corporation Arms', where it's mainly off topic. Way off topic. I guess the best way to explain it is a disparate bunch of people with a common interest who decided that they all (mostly) get on. It's moderated, so trolling and vitriol are kept pretty much to a minimum. Newbies are greeted by none other than Judy Dyble, and Simon Nicol occasionally pops in to contribute when speculation gets the better of judgement. There's a monthly special guest (this month it's Ken Nicol out Steeleye Span, last month it was Simon Emmerson out of The Imagined Village). we had a get together in the country last weekend. http://skirky.blogspot.com/2008/09/across-evening-sky-all-birds-are.html

About three years ago, I was persuaded by my brother to join the discussion group at the Bob Dylan site, Expecting Rain. I did so and enjoyed many discussions there: some highly literate and stimulating, others beyond idiotic. I don't post much there any more.