I cross-posted this on Ravelry and Crochetville, but I think it's that important. Before you read the rest of this, go here and do what it suggests:
Do this even if you're not a senior citizen. Print extras for people you know who don't go on the Net. Here's why:
I took one of these to my neighbor klast fall when we got them in at the fire department. She wasn't interested in filling it out right then and said she and her kids would get around to it. She has a complicated medical history takes numerous medications and had literally a dozen doctors prescribing things for her.
She had a stroke this morning and couldn't talk. (She's doing much better tonight.) All of us neighbors were there when the squad arrived, but none of us was sure what medications she took, and I couldn't think of her daughter's phone number. The for was still on her end table, left blank.
If anything happens and you can't talk--or if you just have the living daylights scared out of you and can't think--this will do the talking for you. For that matter, make one up for your pets if you use a sitter often and your critters have any kind of medical problems.
Just do it now. Someday may be too far off.