Combining a projector with a touchscreen and Android. Sounds like a bad idea until you see the person cooking while scrolling through a recipe on the counter.
I guess if the tablet used leap motion like sensors for gestures that might work otherwise you'd have the issue of messy hands (common state while cooking).
Or a first gen nexus 7, they're piss cheap now too.
Don't know how practical it is but a cool extension would be to mount it on a movable mount on the ceiling and have it pop up on any surface you like.