So I don’t know how this one slipped past me: you can link directly into Open WorldCat via an ISBN/ISSN REST-based URL.

Now any Web site can create “Find in a Library” links for specific titles. The syntax for link URLs is straightforward and keyed on common numeric identifiers.

http://www.oclc.org/worldcat/open/isbnissnlinking/default.htm

For instance, a URL that gets directly to the ARL SPEC Kit on Patron Privacy that I wrote a number of years ago is:

http://worldcatlibraries.org/wcpa/isbn/1594076103