I went to Add-on-Con some weeks back to represent my employer, the Mozilla Corporation.
One of the goodies you get as a registrant was a jigsaw puzzle from the Google Chrome Extensions team.
Perfect, my wife and I love solving jigsaw puzzles. We finally finished a few days ago. Anybody who has started at all will realize the puzzle is of a QR-code. The QR-code is an extension that will eventually lead you to a prize. It was a bit of a mini-puzzle not nearly as difficult as finding the QR code.
Although finding a QR code scanner was a bit difficult, I had to borrow a HTC Magic from Justin Scott and installed a decent barcode scanner.