I know there have been some attempts at this before (done mostly in Java), but I've yet to find one that doesn't seem buggy or off-puttingly complex:
I'd like an application (desktop or online) that let's me develop a set of cards, complete with artwork, flavor text, and rules about how each card functions.
If multiple people have access to the app, they can play via internet access.
The most important requirement of this app would be (1) a non off-putting learning curve and (2) a scripting feature to implement rules sets for games, (3) it should implement a way to "win" collectible cards if the particular game is a CTCG.
This is probably pushing the envelope of proper NANY scope, but we've got 6 months, and it doesn't have to be completely polished by the Dec 7th submission deadline, just functional.