(I've added a zip file link with the full camera size images (6MP), since bandwidth and screen sizes have changed a lot in the decade since I posted these.)
Update:
Found something fun: in the new iOS 8 (iPhones/iPads) you can now select third-part keyboards. In one of them you can put a photo behind the keyboard. I think this one fits well:
(Click on it to see the texture, it's wild.)