Jsexnetwork.com is a decent one for harder to find/retired idols. Their AV actress listing can be a gold mine of names if you're an oldie collector, but sadly they don't provide the videos (or crappy asf/wmv encodes with watermarks if they do).
ActionJAV, I've had memberships with them off and on for a few years. They're awesome. Whoever encodes their high-def stuff could do better. But per volume and ability to easily search for anything, it doesn't get much better. I can't recommend them enough if you're going to spend the money for a membership.
Asia Movie Pass, mentioned above, is another great one. IIRC, they tailored to the bukkake and uncensored crowd, but it might've changed. It's been awhile since I've had a membership, so I don't know what they've been up to recently.
JavHD is mentioned in that link Jugulear posted. They're uncensored, high-def, and it looks like videos might've been produced by them. That would be rare. Most of these sites usually just post the same encode of the same title. I had a three-day pass for them. I think the highest-rated actresses I saw was Azusa Nagasawa and Shiori Aiuchi.
I don't know how "legit" these sites are, really. I'm sure the studios in Japan get some sort of kick back. But I've seen the exact same encode of the same title on three of them. That just tells me part of their content collection is getting crap off the internet like the rest of us. Who knows.
