(There's so many wedding sub-forums I wasn't sure where to post this, but I think this was the most appropriate one.)
Someone on Reddit posted this, saying it was his sister's alternative to a guest book at her wedding. What a neat, clever idea! I love it, and if I ever have a guest book type of situation, I want to do this. (With plenty of baby wipes on hand, of course.)
In case the photo is too small to see inline (if you open it by itself, it's full sized), it's a sketch of the happy couple riding a bike through the air over a house. The bride is holding the strings to a huge bouquet of Up-style balloons... which are actually the thumb or finger prints of the guests, in lovely colors of ink or watercolor, and many of the "balloons" have been signed by the guests with a fine tipped pen. It's so neat!