Brainy Kids at Dana.org. This site has fun stuff for kids and some ideas for lesson plans. http://www.dana.org/kids/
Brain Jokes from a professor at U. of Washington. If you are a fan of brain jokes, you will enjoy this site! They would be fun for an anatomy class. http://faculty.washington.edu/chudler/jokes.html
Neuroscience for Kids - In the News. This site isn't as much fun, but it has many interesting neuroscience- related news articles. These may be good for a class activity/lesson or for students who are interested in neuroscience. http://faculty.washington.edu/chudler/inthenews.html
Did you ever taste music? This short article explains the rare occurrence of synesthesia. http://faculty.washington.edu/chudler/synmu.html
Some brain benders to try for fun. http://www.youramazingbrain.org.uk/teachers/brainbenders.htm
The High School Hub. This site is for students and has a homework help link as well as some fun stuff. http://highschoolhub.org/hub/hub.cfm