http://www.funwithtubes.net/

Jim

Dynaco - Doctor

http://www.dynaco-doctor.com/

Electron Luv

A crossover between metalworker/valve boffin with dazzling designs:

http://www.electronluv.com/

nice! reminds me of 1950's gas stations and malt shops.

IMO, these guys are very hard to beat in audio design. They are simply superb. Even their speaker drivers and horns are simply amazing.

Biasing Basics

http://www.youtube.com/watch?v=Mah6TXRBXHs

Valve Technology: A Pratical Guide

http://www.r-type.org/static/maplin.htm