Looking for an API to pull book information based on ISBNs

How do online bookstores do it?

[volare]

I'm looking for some type of service where I can query it with a book's ISBN and receive meta data about that book in return - namely the title, author, publisher, description, an image of the cover, etc.

There must be a good solution for this, right? How do all of the various bookstores online get their data? I can't imagine it is a manual process.

I've found a couple of things that look close to what I want, but these don't provide a way for me to get an image of the cover.
Example:
[code.google.com...]

[edited by: phranque at 12:12 am (utc) on Jan. 16, 2009]
[edit reason] No urls, please. See TOS [webmasterworld.com] [/edit]

[incrediBILL]

For cover images you might want to look at Amazon's API

Another source is Z39.50 protocol used by many libraries, cover shots may be available:
[loc.gov...]