A games shop in Paris embraced the rubber-sheet metaphor of space-time to guide their interior design. The illusion is so convincing I can imagine shoppers occasionally stumble when their eyes and feet disagree about where exactly to expect the floor.
My only quibble is that I wish the display consoles were in the center of the "depressions," so that I could claim that I was gravitationally drawn to a particular selection. "I'm sorry, I had to buy the latest release. If I didn't, space-time would have been pulled into a vortex of increasing mass density until collapsing into a singularity, and I never would have made it home to dinner!"
I held off on posting because I can't find the original image source to credit, only that it was first talked about by Mighty Optical Illusions. My Google-fu has failed me so utterly that I can't even find the name of the game shop in Paris with this fantastic floor. Please, chime in if you know where it is and a better way to credit the photos!
Update: It's a 2008 photograph inside the Fnac at La Defense by Alex Korting. (Thank you, pixelguy!) Alas, they've broken my heart and redecorated a few times since then, revealing a painfully-boring solid-colour carpet in November 2013. Like all optical illusions, the effect only works from certain angles, so some store visitors were disappointed that the photographs are way cooler than reality. Bah, humbug! My love for space-based interior design will continue to hold onto this as an awesome idea that I'd love to see in nerderies more often.