1. Sorry, deleting references to the site listed here - dispute with owner is the cause.
2. Seikomatic Archives. A Japanese language site that focuses, as one would expect, mainly on "Seikomatic" models. Use a translator link when you access it, but be prepared to puzzle over what the translation really means
One hint: when you see "Playground Seiko" it really means "Grand Seiko".http://www.h4.dion.ne.jp/~smatic/index.html
3. Hokkaido Watch Museum
Another Japan-based website with some interesting vintage items & info:http://www.venus.dti.ne.jp/~osamu/HOME.html
4. Arochan's Watch Collectionhttp://arochan.hp.infoseek.co.jp/
NOTE: on the Japan-based sites, I've not checked all of them recently, so some could have either moved, changed content, or ceased operation in the meantime.
5. For Citizen lovers specifically!
Sweephand's Vintage Citizen Watch Blog | Welcome to the world of Citizen's vintage timepieces.
Good movement table & family-tree diagrams of vintage Citizens (among other great technical & historical detail!!)http://sweep-hand.org/