Actually, there's work being done on one... (Score 4, Informative)

What you're basically proposing is a way to share bibliographic metadata -- not the book itself, but table of contents information, library holdings, etc. There are standards amongst libraries for doing this (ISO Z39.50 and AACR2--both of which are horribly abstruse and generally a pain to deal with). Dr. Rob Cameron, along with a small group of Simon Fraser University students, has been working on the seeds of a system for sharing bibliographic metadata -- see http://www.usin.org. This basically extends the URI standard to support ISBN and ISSNs, initially to support scholarly communication, but also making it possible to create what we call "personal bibhosts" with support for annotations, shared notes, etc. Among other things, we've implemented searches across various worldwide libraries to obtain and compare bits of bibliographic info, and so forth. Yes, you still run into the problems of inconsistent data for a given ISBN/ISSN (as a previous poster pointed out), but hey...you have to start somewhere!