I't so funny that I was reading down this two page list and I have every single one of those in my favs folder already.
Pete Millet's site is an immense wealth of literature! I've downloaded so many books from his site. I've emailed him about some old MacIntosh Amps I have. Nice guy.
Here's a several other resources that I've used in the past that I didn't see on the list yet:http://boozhoundlabs.com/
some great diy tube projects/articleshttp://www.dogstar.dantimax.dk/tubestuf/index.htm
Fred's site and home of the Real McTube I & IIhttp://www.harpamps.com/
another great resource of informationhttp://www.lwharpamps.com/
Some great diy projects and forum for small Harp amps.
And Don't Forget: http://www.brownnote.net/
Hit up the forum for a wealth of information! Some really knowledgeable guys there.
Oh and Finally: http://www.diyaudio.com/forums/
While mostly dealing with Hifi there is a wealth of knowledge there regarding tubes/SS/Speakers, etc...