I've always appreciated having someone (a skilled professor, a peer, or an upperclassman) point out interesting things in whatever I am studying. That way, it's easier to get "the point" of the subject or lesson. A lot of textbooks are designed to complement that aspect, rather than to provide it.

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?

Most text books are riddled with errors. So I guess as far as content goes the value of groups will be in correcting such errors.

(And perhaps also in better explaining the material by adding notes and linking to external content.)

Yeah, that's been happening on Curious Reef a lot (Curious Reef is my website which is similar to OpenStudy).

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.

I had similar experiences.

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.