NESWORLD - Everyone loves the NES. If you don't, then there's probably something wrong with you. This guy loves the NES more than anyone else, and has a website to prove it. In fact, reading about the massive number of Famiclones out there generally kick-started my interest in console collecting. Go take a look.
Console Database - Has a wide variety of games information, but what we're interested in is the console information page, which has short snippets about consoles ranging from mainstream to the extremely rare. Provides technical information as a bonus.
The Ultimate Console Database - This has got a lot of stuff on it that I had never seen in my searches, include an awesome list of Famiclones and clones of other consoles. More importantly, it's a bloody good read too.
Digital Press - Has been distributing a fanzine for videogamers and collectors since 1991. Even without that, the most useful part of the site is the online rarity lists, which cover most systems you could want to get info on. The only trouble with this is that it's obviously US-centric, and so the rarity listed there may or may not have any relevance to the scarcity of a game here in Australia. It gives you a rough idea, however, and is certainly a good way to add to your ability to detect a good deal.
Something which Digital Press is involved in and is definitely worth a look is the Classic Video Game Syndicate, a webring bringing together a huge number of site devoted to the joy of the 8-bit, the popular and obscure. I've applied to be part of it, and you should be too.
