One of my favorite website ideas. It's a little too neo-luddite for me in it's marketing, but I applaud the struggle to give power back to the people (even if they can't put the toothpaste back in the tube).
Problems of privacy with social media sites are legal issues as well as practical ones. This article reveals various cases of employers (and schools) probing for personal data from subordinates.
More on the privacy theme. It's not just about students posting things that they'll regret later, it's also about making laws that protect us all from grasping superiors.
As with other content on DailyTekk, this has an e-commerce focus, but some of these tools may have educational value too. (I'm thinking particularly of the grouping, filtering, and visualization tools.)
A powerful reference database that can be used to keep track of sources and also integrated with word processors to generate bibliographies and such. This does a very good job of importing metadata from websites and online texts, and pulling additional information for sources from other databases. It would be nice if this were a bit more customizable, but it may get there in time. The folks developing this are very helpful and responsive to users.