Escher-like paintings
Wow. I think I have another favourite artist all of a sudden. His name is Rob Gonsalves, and his paintings are very satisfyingly Escher-esque ... and there's a lot of them! Now ... if only I could afford purchasing one of these guys. The trouble would then be, I guess, picking one of them! I think this one's my current favourite, but really, they're all very stunning.
Here's some more links to galleries and product pages.
Heraldk