I would suggest forcing the SSL across the board. I know, I know, I can type it in BUT it is just nice to have the little things work all on their own, even when I am logging in.
This is pretty damn rad. Personally, I would love to see an extension of this with a "pop-quiz" module that asks 3-5 questions with multiple choice answer. Think, text-books.
Congratulations on your development. It seems this has been done before, and albeit it is neat what is the benefit over a low-cost "standard" webhost? I can name a few webhosts that are in the $3-5 range and offer standard tools and the ability to install a SSL.
I have always felt that OwnCloud was just a personal "fun" alternative to great services like Dropbox. The DropBox business package, for the price, is not bad all in my own opinion.