Ask HN: Light-Weight LMS On The Cheap

This question may have been asked in the past so forgive me if that's the case. For some time I have desired to create a LMS (learning management system). Part of my desire to do so stems from the fact that I have a lot of friends and relatives who teach, not to mention, I think it would be rewarding to contribute to the education of others. So the question for my fellow entrepreneurs is, do you think there's a market for a light-weight, low-cost LMS with a heavy emphasis on Facebook like social features? What kind of research could I do to find out if there is a market? Thanks .