What I was thinking, besides a shot of the empty "jar" or whatever that is in Dr. Mario, is maybe to take a screenshot of each Level. If I recall correctly, there are 20 selectable Levels, and though it goes beyond 20, I'm not sure that there are more viruses after that point. The placement of viruses is probably random, but you could explain somewhere on there that these are just possible random arrangements and just serves to give an idea of how much stuff you have to deal with. Also similarly, in Tetris (the Nintendo version, as opposed to the Tengen version, is listed on the Nintendo Power topic), doesn't the background change colour at certain points? You could also take a screen capture of the multiplayer screen in Dr. Mario (again, with the different Levels), and though this isn't really a resource for sprites, I think in both Dr. Mario and Tetris it wouldn't hurt, if you just wanted to fill space, to show all possible pieces in all rotations. Just some ideas so we can go beyond a mere screenshot.