Like already mentioned, I would think that a card like this carried in a wallet would be sufficient

Name:
Phone #:
Emergency Contact 1:
Emergency Ph #:
Emergency Contact 2:
Emergency Ph #:
Primary Physician:
Physician Ph #:
Medical Info:
Prescribed Drugs:

etc.

For personal information carried on a thumbdrive to be used by you (like CC#'s SSN etc.) I would make sure that information was encrypted! Something like a self-decrypting .exe file with a password that couldn't be cracked (in any reasonable amount of time - obviously you wouldn't use your last name or phone number on this one)

PGP or GnuPG would be a good start for encrypting a text file with such personal information on it.