Looking for geotagged book data sources, available as (in order of
preference): apis, share-able dataset, crawl source. Ideally this data is
indexed by lat/long, but any geographical groupings are valuable.

Here’s what I have so far.
http://openbooklab.com/looking-for-geotagged-book-data-sources/

Are you interested in geotagging your book content?
http://openbooklab.com/how-to-geotag-book-content-in-four-steps/

Thanks, John