Review my new learning website: Crunch Course
czcar: One of the first things I would think about is charging.I am sure there is a definition for it - but the act of paying some money - whether it is incentivised by returning a percentage of the money dependent on commitment/progress etc, or is taken as a running cost, has the effect of increasing dedication/loyalty and filtering out the people who like the idea of learning it but aren't willing to actually learn (or so i hypothesize...)If you haven't - have a look at Clayton Christensen's "Disrupting Class", "The Online Learning Idea Book" - Patti Shank and "New Designs for Early Education" - by IDEO (its aimed at early childhood but some of the ideas revolving around increasing user involvement are really interesting). They delve into some extremely interesting ideas, not all relevant but theres some gold in them.And I have not done nearly enough research into it, but I believe an understanding of Game Mechanics and how effective Social Interactions work on web would probably paramount to the effectiveness of this web app (theres a tonne of this info out there - think zynga/gowalla for learning).Just my 2cents