One of the things that set V&V apart, I think, was that they included comic pages and such with the game modules. I have done a couple in the game modules I've illustrated, too, just for that reason. I started the Cover-Op thing hoping I'd get a few cover commissions from people.
Yes those comic panels really helped to stage the adventure in the minds of the players and game master. Cover-Op is a great idea and I really hope that it works for you. Do you colour these as well or just offer them as line art?
I had planned just to do the line art. I hate coloring on originals, I do most of my coloring digitally. I love the UNDO function. But, I'd do digital color like I did on the novel cover I did, last year. It's too bad the book didn't work out, because that cover came out better than I had imagined.