I challenge the Cardsmith community to create a Flip Land. I won't mention any DFCs we might be getting in Shadows, for fear of spoiling it for those who want to remain clean. Except, in Innistrad, DFCs are usually creature to creature.
If you are not familiar with a DFC, the closest thing we've had recently was the Planeswalkers from Origins. With Shadows Over Innistrad on the horizon (Releases the Saturday before my Birthday!), FlipCards are becoming known again.