Animated Engines www.keveney.com Great site explaining different motors throughout history. Each motor has an animated example which gives you a great visual of how it works. I love it when a web designer actually uses their brain.
		Amal Carb Tech Tips www.hitchcocksmotorcycles.com This site does an admirable job of explaining how to make your Amal nightmare become a tolerable experience. Frankly, you're better off turning this carb into a desk lamp or perhaps a cool beer tap. Good info, have fun.
		British Serial Numbers www.britishspares.com If you own an old BSA, Triumph or Norton, this site will help in identifying what year and model your frame and/or engine is.
		Harley Side-Valve Tech www.victorylibrary.com This page has various articles focused primarily on Harley side-valve era models. If you look through their site you'll find some decent books on other bikes as well.
		Fraction to Decimal Conversions www.math.com Great table that displays many common Fraction to Decimal conversions. Every shop should have this hanging somewhere.