Does anyone know of an online guide to the the different grains. What I'm looking for is a nice chart or something listing which malts are considered base malts, and which can't be converted in mash.

Ditto... perhaps one that tells a bit more about the specialtys and malt types... like what is the difference between Munich and Vienna etc.
BUB (boob)

Try this one from John Palmer's "How To Brew".

http://www.howtobrew.com/section2/chapter12-1.html

Wayne
Bugeater Brewing Company