This website is linked with the Smithsonian Institute, and it is a good search engine for teachers looking to build lessons around artifacts found in the Smithsonian as well as other parts of American history.

This page gives a few suggestions for lessons you can do with the Holocaust and WWII, a potentially touchy subject with your students.

This site just has some general activities that you can do with your students if you are teaching about Greek mythology, and I think these would work well with other types of mythology too.

This website gives many links to different historical figures, time periods, empites, etc.

The site gives alot of useful information for teachers and students, having many primary sources, examples of syllabi, and teaching strategies for U.S. history.