WOW! 21 sunts and no one ever offered me a card from the manufacturer. Then again, the bulk of my work was done by cold and arrogant surgeons. I wore a MedicAlert necklace for a couple years (15-17) but my body does not like jewelry of any kind.
As an adult I carry a USB flash drive clearly labeled MEDICAL, along with my other flash drives. On the medical, all of the documents are in PDF format. One is an exhaustive medical history, complete with my current doctors and medications and supplements. Another is my routine lab work for the last two years scanned and sequenced backwards. Another is my Advance Medical Directive, Virginia's combination power of attorney, living will, and direction on anatomical donations and disposition of remains. The only other doc is a file of notes I take to every doctor visit. I print off the medical history and labs for every first visit with a doctor.
With the pervasiveness of field laptops for emergency workers and the ubiquity of ER computers, I encourage others to be this painstaking in maintaining and carrying information. My wallter contrains a card pointing to the flash drive.