Does anyone know if there a website that lists certified registars for ISO 13485, similar to what the OASIS website does for aerospace/AS9100??

This isn't exactly what you asked for but it's Health Canada's list of registrars that they recognize for the Canadian Medical Device Regs...
http://www.hc-sc.gc.ca/dhp-mps/md-im/qualsys/list_liste_regist_2_e.html

No, there is no central repository of ACCREDITED CB's for ISO 13485. You would have to go the different Accreditation Bodies websites and search their Directories.

Does anyone know if there a website that lists certified registars for ISO 13485, similar to what the OASIS website does for aerospace/AS9100??

From the ANAB site:

HSB RS-1217904-HSB CT dba HSB Registration Services
IMS-1301643-International Management Systems, Inc.
ISOQAR-1301651-ISOQAR
NQA USA-478089-National Quality Assurance, USA
NSF ISR-1301672-NSF International Strategic Registrations, Ltd.
PJR-551582-Perry Johnson Registrars, Inc.
Stijloor.

Consider this list of Notified Bodies (http://elsmar.com/Forums/attachment.php?attachmentid=6958&d=1181928075).

Just a note of caution, there is no obligation for one registrar/Notified Body to "blindly" accept the certificates of another*, even ones that are accredited.

It is the duty of any subsequent registrar/Notified Body to base their certification decisions on evidence that they have adequate confidence in.

Whilst this might potentially unfairly count against a smaller or newer registrar, at the end of the day it is entirely your decision as the purchaser of the service. Find a provider that will give you not just a certificate, but a certificate that will meet all of your requirements.

So always be a little careful in your selection, especially if you are a supplier/subcontractor seeking ISO13485.


*(There is a clear understanding that EC certs will be universally recognised between Notified Bodies unless there is a good reason not to accept an individual one.)