gameofjapan.com are safe and reliable, I use them a lot. The only potential problem is that they aren't very specific about condition so if you absolutely must have spine/reg cards then you're probably better off shopping elsewhere. Having said that though B grade games (which seems to be at least 90% of their stock) is usually in very good condition and includes whatever extras it was supposed to.
My other recommendations are -
Play-Asia: can be expensive, but they're a great "one stop shop" and carry pretty much anything game-related you could want (art books, CDs, figures, etc)
Yesasia: Much like Play-Asia, but with a greater range of Asian DVDs/books/comics.
Japangamestock: Website doesn't exactly look fantastic, but they're reliable.
http://www.nin-nin-game.com : Bought a few AES games from this shop - perfect service, no complaints.
http://www.eurotaku.com : Where I bought a good chunk of my doujin games from
http://www.amiami.com/ : Game selection is limited, but they'll often have preorder bonuses that no one else does. Shipping has to be calculated by them for each purchase but whenever I've used them it's always been reasonable (no sudden $50 EMS ONLY charges on a $5 item) and the packaging is fantastic.
http://www.neoamusement.com/ : Bought a few bits and bobs from this store, including a soundtrack CD. Soundtrack arrived quickly, cheaply, and was genuine so no complaints.
http://www.paletweb.com/ : Great selection of used games and new doujin. Reliable but (apparently) prone to banning people forever for cancelling orders.
Hope those help someone out
