My local library is part of a network [1]. When someone recommends a book I can go to their site, look it up, and request it. Then they send it to my local library and email me so I can go pick it up. This is nice, but it could be better: what if the library could mail my books to my house, and I could mail them back?

[1] This has long been my favorite example domain name: mln.lib.ma.us. The Minuteman Library Network goes under libraries in Massachusetts which is in the United States.