Amazon. Some time ago I placed several orders over the course of a few weeks, with multiple books in each order. About a year later realized I had never received one of the books. I e-mailed Amazon, and they shipped it right out to me, no questions asked. No quibbling about how long ago the order was, or messing about asking for order numbers, delivery receipts, etc. Just a simple "We're sorry, here's your book." I was very happy that I didn't have to jump through a lot of hoops on that one.