I was thinking it might be nice to have some sort of networking setup where a module could be designed around having two (or more) players, (preferrably with support for both turn-based and real-time modes) with proper story and quest structure - a host could start and save games, and (if the module specified it as a requirement), both players would be required to connect in order to continue play.
I realize this would take a lot of effort to implement, but it's an ideas forum so I figured I would throw it out there.
