The Franklin Institute
Resources for Science Learning: The Human Brain
Everything you wanted to know about keeping your brain healthy. How should you nourish your brain, how should your brain be protected, and even how to "renew" or stimulate your brain.
Other
Dana Sourcebook of Brain Science: It's Mindboggling!
Look through this online pamphlet to find brain exercises as well as explanations of how the brain works. Very complete and fun to read.