There's quite a buzz in the book business at the moment to encourage people to buy books for Christmas. This has even resulted in this video being produced:
For what it's worth, I'd like to add my voice to the call. You can buy one to suit anyone, they're great value for money, there's more pleasure in them than most presents, they're easy to wrap... and you'll make an author somewhere have a warm glow. I'm not saying you have to buy my books (though it would be nice - A Brief History of Infinity's a good present choice) - just buy books. Please!