Adobe Education Exchange is an online community of educators who share resources, ideas, tips, and more. It launched at ISTE 2010 and now has over 75,000 educators sharing over 4,000 resources.
They just re-launched it with some new features which you can read about here: http://blogs.adobe.com/conversations/2013/02/announcing-the-all-new-adobe-education-exchange-education.html.
The new version includes simplified navigation, a new design, easier browsing of resources, increased social/community features, and API's so that it can integrate with other apps and platforms.
It's a great, free resource.