I like finding books people leave in airports. I figure they're done reading it, and they don't want to carry it, so they leave it for someone else to read, just sitting on a seat at a gate.
On my way back to Ontario from California, I saw someone had left a book. I quickly recognized it as book meant to recruit Christians. Some Christian had left it, hoping someone without a book would find it and possibly become Christian.
Those who know me will be able to guess what I did with the book, with great delight.