Resource sites are tricky things. There are so many different requirements for the many possible game genre out there. I know I even have trouble finding good sources of quality content to use. Maybe a list of sites and what artwork they offer would help, but these will change over time anyhow. However if you want to start an indie artist for game dev site, that would be a project or site of it's own. A neat one mind you.

Another topic which could help a lot is math. Paul just posted about circles and arcs, which uses some basic trig to solve. You ever notice how your old highschool's math department took care of all the computer science courses or if you did have a computer science department it was paired or overlapped with the math department? Knowing the math and being able to apply equations to code are sometimes two very different things.