#1
I know a lot of us are learning and using music theory to a certain degree. I also know that there are a lot of sites including this one with lessons and supplemental material. Basically, I am asking that if you know some of these sights, post them here.

Here are a few (other than UG of course that I have found.

http://www.ibreathemusic.com/
This site is a lot like UG, but it has a lot of articles on everything from power chords to advanced theory.

http://www.theorylessons.com/index.html
This one is still in the process of construction, but it looks promising and has some great material on modal theory.

http://www.musictheory.net/index.html
This is one of my favorites. It goes from the beginnings of written notation to the most in-depth theory. It also has many useful trainers and utilities such as staff paper generators and chord calculators.

If I were you, I would also invest in some books on music in general. Some high schools like mine offer theory classes as well.
"I worked hard. Anyone who works as hard as I did can achieve the same results.” ~ Johann Sebastian Bach