I read sega-naomi.com occasionally, pretty much just deals with the Naomi system. Also neo-geo.com, mainly neo but people generally talk about all types of gaming, mostly newer stuff not so much classics (Pac, DK, etc.). ArcadeOtaku, kinda like Neo-Geo.com but mainly people over there are all about Japanese Candy Cabs, so if your looking for one that's a good source of info.
I also read RGP a lot and a couple local area pinball boards.
Dennis