I've only been a member of Japan Today com and left, pissed off with the queasy combination of little arseholes writing bullshit and politically correct moderators who don't understand the difference between pointing out flaws in Jp society and thinking (expressed in non discriminatory terms and taking care not to generalise when it's inappropriate) and 'racism'. Empty vessels using emotive terms to censor people who can use logic.
I've seen Gaijinpot com and think it's good. Numba 2. Lotsa topics, some excellent advice from old hands like that PaulH bloke who's also on Eslcafe and that mysterious woman called Trip Hop, some heated discussions/arguments, you're allowed to give other posters a real rollicking if they deserve it, and even racist wankers are given enough rope to hang themselves.
Lets Japan ranks Numba 3. Some great shit going down there, not so broad as gaijinpot but entertaining. Another site that understands what's racist and what's not and doesn't waste its time running yapping at the heels of the very to completely politically incorrect.
Eslcafe is Numba 4. More serious (grates at times) which is usually very informative. Big flaw is the censor happy moderators (not all of them) who don't understand that adults do not need protection from heated discussions/arguments. Prone to seeing things like Big Brother overlooking the captive posters, close topics that go on in personal disagreements even when there's no real trollish activity but posters who'll keep presenting their case.
Loser sites - Big Daikon. Yeah, I've known some great JETS and got pissed with any number of them but they're full of shit on that discussion board.
The Foreigner-Japan one is schmaltzy and seems full of females rapturously singing the joys of the generous, hospitable, correctly mannered Japanese living in harmony with four seasons. Some good topics but the scrubbed face view of the Japanese most of us know as great at putting on a face for those who live in Japan for less than a year is fricking irritating.
Had to laugh at one topic in the archives "Japanese Culture - My View" or something similar where the starry eyed girl's post is as irritating to the experienced as tin foil fillings. Some experienced Japan hands posted comments about cases where the same people (ie the Japanese) had used them and warned others about taking all the tatemae stuff at real face value. Onya!
Fukuoka Guide (or "Wayne's World") is another serious site with info about Fukuoka and Kyushu. Okay on the info, pisses you off to see the photo albums where the bald boy gaijin himself (maybe his name is "Wayne Kerr"?) poses nude as he must show us how he gets dressed for a Fukuoka festival for the Yamakasa.

Yeah, well some of us blokes don't get a hard on from wearing the fundoshi and from seeing other blokes wearing it. But remember - it's the 'culture' that interests the bloke... snicker. Add to that a shit discussion board where mostly nobody ever posts except for Wayne and probably his friends, and well, let's just say it must do wonders for some egos having their own websites on Japanese topics. Especially men wearing fundoshi ...

Fucked Gaijin Rules!