I'm guilty of buying most of my books from amazon or B&N.

I like building up my library of books. I can go back and dig through them again if I want. I can make annotations, rare as that may be. If I love a book I can loan it to a friend. And sometimes they just look great.

I have a strong preference for hardcover books, and sometimes I'll spend a long time picking out just the right version of the book that I think will make a great conversation piece.