I'm working on a project that involves collecting information about the
books that people own, and the easiest way to do most of that data
collection is to collect just the ISBNs for those books that have them, and
photograph the title pages of the books that don't. This gets me out of
people way quickly and lets me do my data processing later.

I've asked OCLC about the requirements for getting an affiliate ID for
using their APIs for the project, but while I'm waiting for that, I'm
looking at the Open Library APIs.

The documentation for the APIs is weak, and it looks like it hasn't been
updated for a while. Has anybody used them much, or know what the state of
ongoing development of them is?

All I'm really looking for at this point is a way to convert an ISBN into
basic bibliographic data, and to find any related ISBNs, a la OCLC's xISBN
service.

- David