Riding the wave of the CSI craze, HSI - Historical Scene Investigation is a ingenious way to teach history. The site was created by a consortium of colleges and the US Library of Congress in is based on Social Studies/History standards.
There are 13 "open cases" for teachers to choose from, with topics such as children in the civil war, the atomic bomb, and the Boston massacre.
Each case poses a question about the topic and has resources for both teachers and students. Students then use the resources on the site to answer the question(s) posed at the beginning of the case.
This is a great resource for teachers to incorporate more project based learning and critical thinking into their classrooms. The site has come up with some great topics and provides excellent resources for the students to use. One of my colleagues who teaches history thought it was great and is using some of cases right now.