xISBN [OCLC - Projects]

Found this via Catalogablog. You have a paperback book in front of you--and you can't find a gosh durn OCLC record. That's because OCLC only has a record for the hardback (or maybe audio) edition. Well this handy little experimental OCLC service will find related records based on ISBN. Give it a whirl!
xISBN [OCLC - Projects]:

As an experimental project of OCLC Research, this service is available without charge or guarantee. Access does not require registration or authentication. OCLC reserves the right to modify or discontinue the service without prior notice. The xISBN server is believed to be stable, have good uptime, and to have the capacity to handle a reasonably high volume of requests without a significant degradation of response time or service failures, but OCLC does not guarantee service levels for experimental systems.