Qwiki allows users to learn more about a variety of topics through multimedia and storytelling. Users can also contribute content to make Qwiki even better.
"Mash your ideas and media together with friends in a dynamic whiteboard wiki. Using photos, videos, and other web content you can instantly create brainstorms, presentations, scrapbooks, and enjoy an interactive chat with more than 50 friends."
My students told me about this site where they make study guides and flash cards for themselves. It's free, and it would be particularly good for studying information that you have to memorize.