If you ever have to have an unfamiliar person giving somebody CPR the best thing you could have is this:

CPR Prompt® Rescue Aid
This is an actual device that walks you thru the CPR steps.

Now something that I learned working in the 911 system in NYC. You can save 1000 lives and no one will notice but that's ok it's my job. But loose one and you will hear about it for the rest of your career. Even if CPR is a simple by the numbers (or letters) task there is so many things that can go wrong. Lets say you passed out and person goes to check your pulse at the wrist (cartoid pulse) and comes up with no reading. No pulse, you should start CPR according to the card. Well cartoid pulse will only register if you are 75 and above. By starting compressions and ventilations you just succesfully interupted heart rythm and blood flow. Now lets say you just felt down the stairs and this time you really have no pulse. Person whips out a CPR card goes to the first point which says: "...establish the airway using head tilt chin lift". They go for it and agrivate possible spine injury even more. I don't even want to go into trauma scenarios. In the end even if the person knows CPR but basic body substance insulation tools are not there (gloves, masks) the chance is, that person will not do it for you. Loved one or a friend yes, but total stranger no.

Personally I'm a strong supporter of the mandatory CPR course when you get your DL.

Matt