I had a thought the other day while comparing the difference between physical media and digital libraries and thought it would be cool to establish some way to "borrow" movies from friends in a digital format.
If you could give "Borrow Rights" to members of your friends list then they could remote connect to your library and stream files from it. The way to make this different from file sharing and possibly legal would be that while a file is being "borrowed" it could not be played anywhere else. It would mimic the physical media in that aspect and I assume it is not illegal to let someone borrow a dvd.
I don't how it would all work because i'm new to the networking/file sharing/ torrent thing, but I think making it so that the file is not copied and it is only viewable at one location at a time, then I would think that wouldn't be illegal.
Just a thought.