For a good time I wrote a program called Send It To Me exploiting
(uses) xisbn and thingisbn as well as X-Server and SRU:

   http://mylibrary.library.nd.edu/send/

Given an ISBN number the program will try to find the item in our
local catalog and prompt the user for their University ID if it is
found. The system would then update a local database and get somebody
to actually send the item to the user. "Send it to me!"

If the item is not found, then it uses xisbn and thingisbn to
generate similar ISBN numbers and search for those locally. Again, if
found, it prompts the user for their ID and sets up a delivery
mechanism.

If all is lost, then the system locates the item in the Library of
Congress, and offers the user four choices: 1) ILL, 2) library
purchase, 3) user purchase, 4) find similar items and borrow them
instead.

The whole thing is just a prototype; it demonstrates how libraries
could make things easier for students, instructors, and researchers
when it comes to acquiring known items from library catalogs.

--
Eric Lease Morgan
University Libraries of Notre Dame