Enter a problem, and a unique URL is created. Once shared with others, a group can collaborate by adding questions, comments, solutions, etc. Very easy to use and effective way to solve problems.
Very handy tool lets you share just a portion of an online video. You select the start and end times, and the site gives you both an embed code and link to the video snippet.
Very useful tool for finding images for student projects. Enter the search term, select Educational for Permitted use, and check "none" for requirements (doesn't even require citation).
Brand new site that puts videos from YouTube, TeacherTube, SchoolTube, National Geographic, etc. all in one place, organized by age, subject, and curriculum order. VERY cool class resource!
Nice site to teach kids how to create and code mobile apps. Very good, easy to follow tutorials, and apps can (for a fee) actually be sold through the Vizwik app store or other app stores.