Here are four sites I recommend:
Magweasel - This is, in fact, the best gaming blog on the entire internet, the writer is a freelance translator who catalogues weird Japanese gaming stuff, like Super Mario Bros. guides and electromechanical arcade games. Consider it essential if you're a PC Engine fan- he has a whole category called "I <3 the PC Engine" which
you have to read right now go go go.
The Simple Series - I've mentioned this before, and doubtless will mention it again, but it's worth mentioning as many times as possible. A not-quite-but-basically-there listing of all the Simple 2000 Series games- that infamous series of cheapo PS2 games instigated by the sinister cartel known as D3 Publisher, a series that spawned games like Earth Defence Force, Splatter Master and the shameless Onechanbara series. Additionally, it lists their European name where applicable, so it's really handy for PAL collectors. Sadly, the same site's
505 Game Street listing isn't nearly as complete (although it lists some of their cancelled localisations, including Castle Shikigami!).
Jeff Vavasour's Game Page - Just the one page, but this is a catalogue of all the games Jeff Vavasour worked on. Who's he? One of the big guns at Digital Eclipse (now Backbone) who you may remember as the people who brought you Midway Arcade Treasures/Atari Anthology. He talks about all the projects he's worked on (including the GBA Spyro games) and it's very interesting to hear about this sort of thing from inside. Definitely something for Atari fans to check out.
SelectButton - I got hooked to their (sporadic) front-page updates, podcasts and forums because of their fighting game thread during the build-up to MVC3. While not specifically tailored to retro gaming, their Galaxy Oddity threads are essentially 'video games are
weird, man!' which encompasses all eras. A bit on the strange side, and the forums are not for everyone (I don't post there very often, I just lurk) but you've got to admire
threads like this immense, near-maniacal love letter to Castlevania: Harmony of Dissonance.
... Is this the bit where I plug my own site? Just click the thing below. It's three years old now, which is terrifying.