The LibraryLookup project is almost five years old, and people are still gradually discovering it, as I’m periodically reminded when I get a flurry of emails such as was provoked by this Lifehacker article. I think it’s time for this idea to graduate from the realm of hacks for adventurous people, and enter the realm of normal capabilities that everyone takes for granted.
For starters, if your system supports searching by ISBN, I suggest that you offer — in addition to whatever syntax you already use — one simple and standard pattern:
Next, use the OCLC’s xISBN service to expand the search to include all manifestations of the work indicated by the given ISBN.
Finally, have each instance of your system publish the bookmarklet made from these ingredients on its home page, along with instructions for using it.
For extra credit, enable patrons to indicate wish lists of books they’re interested in, and notify them when books on those lists become available.
People like this stuff when they discover it, but as yet not many have, and until it’s baked into your systems, most won’t.