I wish there was a library through the mail. I got a Seattle Public Library card, and I haven't used it once. The books area spread out across a whole series of different buildings, and it's too hard to find out if the book you want is available at one building versus another. I wish they offered an option to check out books online and have the book shipped to you, and then when you're done you could ship it back to them and get the next book on your list. Like Netflix for books. They could even charge a monthly subscription fee. I bet it would be net revenue positive for them.
Of course, the problem with books is they are bulky and a pain in the butt to ship (unlike DVDs, which are of a uniform, compact form factor), and there are lots of them so it would be hard to keep all titles in stock. I could live with the latter. Maybe the solution to the former is to only allow books of a certain size to be available through the mail, and to always use book rate to ship them.
I spend too much money on books.