I understood the question to be what could YOU leave behind to facilitate identification of YOU if deceased or unable to interact with the authorities.

The first attempt to confirm identity will be fingerprints. You COULD leave a fingerprint card (you can find numerous private agencies to provide one) with a trusted party.

The second layer will be dental. The coroner/police will consult a forensic odontologist (dentist) to look at x-rays of the deceased and compare to x-rays from a dentist. So if you have a dentist who has taken x-rays of you mouth, you can leave the dentist's name with your trusted party: the coroner will probably insist on directly contacting that dentist for a copy of the x-rays...so I don't know if giving a copy to your trusted party would be of any help.

In spite of what you watch on CSI, DNA will be a bit later in the evidence chain (cost, time frame)... but you could leave a lock of your hair with the trusted party.