Just thought of this idea on the way home, which might open up the competition a bit and add a bit of fun: A Deck of Trek
Basically you choose one playing card from a standard deck of 52 cards (plus jokers) and interpret it in a Trek fashion. The Trek element can incoporate the number and suit as an integral part of the design or merely have it emblazoned on top of your own composition. The design itself could be a drawing, 3D model, photoshop - absolutely anything at all. The only constraints would be that the output must be able to be presented in the dimensions of a standard playing card (whatever that is) and that you'd have to state the card you'd chosen at the beginning to avoid duplicates. It would be interesting to see how much of a full deck we would end up playing with.
I've seen this sort of thing being done for charity and the like by celebs (though I'm of course completely unable to find a link) and the results can be extremely varied and imaginative. D'ya think it could work?