Someone on Ravelry posted a photo of a knitted QR code (one of those weird-looking, pixelated squares of black and white dots that you can scan with a smart phone). Better yet, it works. (As in, you can scan it with a smart phone and get sent to the intended URL.)
A quick pattern search reveals that this isn't the first time someone thought of doing that, but it's the first I'd heard/seen of it.
If I knew
Still, a neat idea, and I just can't get over the fact that it works!