I have to say I'm more inclined to detailed textbook-style information than the social aspect. OpenStudy didn't quite manage to deliver any greater value to me, just kept me occupied. Maybe I'll revisit now that it's out of beta and the community had probably grown substantially.
I've always thought that people teaching other people required a tight feedback loop and was difficult to do not in person. I'm curious, did you notice that kind of interaction going on at OpenStudy?
(And perhaps also in better explaining the material by adding notes and linking to external content.)
Here's an example of people working through an issue in a C programming class: http://curiousreef.com/class/programming-in-c/lesson/1/assgn.... There wasn't any issue with the actual book itself, but the discussion is adding value to others who might come across the same problems.
The one thing that I wish I had was basically, "Pick a language and learn Computer Science" course list. So you'd start with learning the language, then do algorithms and data structures, then do software design and you could work your way through all that.