Just to make sure that you are completely overwhelmed there’s also some stuff on Chris Smith’s Coyotebanjo page. In particular the one called “modes” and the one called “substit”. In addition there’s other interesting material there. Stuff on learning by ear.
Do yourself a favour. Read the stuff he writes on topics and styles that you don’t even think you’re interested in, especially the ones you’ve never heard of. He’ll turn you on to some of the most wonderful music in the world. I have very eclectic tastes and when I found this site I couldn’t believe that this guy was in to so much relatively obscure stuff I liked. So I checked out the stuff I’d never heard of and found out about even more great stuff.
The web is loaded with stuff on music theory, just about every facet imaginable and some that aren’t (if not for the web I would have never have heard of microtonal scales, for example).
I lost my favorites when my computer was stolen, but if you search (at google or what have you) on specific phrases you’ll turn up a lot of good stuff. I.e. searching for things like “circle of fifths” (include the quotes) “intervals,” “chord substitution” (again, include the quotes), “scales and modes”, and so on will usually turn up a more useful list of sites than searching for “music theory.”
