Grockit is an online social learning community--good for test preparation for SAT, ACT, GRE etc. Of course, they are trying to get you to purchase theiri online test preparation program. Might be helpful to persons working with secondary learners.
Spaaze is free (at this point)--cork board that can be used as a display board--video, mp3, digial images and more. Might work well for a project summary (group or individual).
Glogster is an online FREE interactive poster tool. Ability to add hyperlinked video, insert digital images and voice (mp3)--lots of ways to personalize. Great potential (e.g., introduce self in course, individual book reports, group projects). EASY to use.
I just found this this week!! I love it. I think I might use it for our WWII unit, or disUtopian book reports, or as a culminating activity for my postcards from the past/postcard to the future workshop! So many uses!!