There are too many out there for me to give any kind of full list, but here are some of the ones I keep coming back to:
Low End Mac (LEM) is simply one of the best resources out there for Vintage Mac users. They offer hardware profiles for what I assume to be the entire range of Macintosh products, as well as interesting articles and many other links. My opinion is that LEM will get you anywhere else you need to go in the world of Vintage Macs!
Here are a couple others that are very useful: