http://lore.com/ LORE is a free LMS that allows instructors to set course to public or private. If designing a MOOC, the instructor can design the MOOC within LORE in private mode, then release the MOOC upon completion.
LORE also offers facebook like interface (discussions appear as drop down feeds, and students can reply to each feed). Gradebook is also customized to individual student (student can see their individual progress).