I thought I was going to see an unresponsive person checked for id by the paramedics/cops on my ride home tonight after I called them about the guy face down on the ground by the MUP, but it turns out they knew him so well that one of them had his birthdate memorized and knew he's changed his shirt from earlier today. Looks like he'll sober up at the er again.

like some others I carry my driver's license, a credit card, and a 20 dollar bill in a thin plastic wallet in my jersey pocket. I have my old GI(government issue) dog tag which has my GI serial no., blood type, religious affiliation, and name. The GI dog tag also has a notch to keep your mouth open so one's body will not bloat in case you are not alive for awhile. I might wear the dog tag on a solo century or a mountain ride, hopefully for the blood type info only. I usually have a cell phone in the energy bar pouch in the Bento bag. The cell phone will have all the pertinent phone nos. which most people should be able to figure out.

Sinch

That's exactly what I do. I have an ID holder that can be separated from my wallet, so I just stuck a printed card in it with my ICE info and blood type. I always carry the ID holder in my jersey pocket anyways, so that method is sufficient for me. Plus I hate wearing bracelets. My friend does the same thing too and he was involved in an accident with a car and the EMTs were able to get his allergy info from his card (the friend is perfectly fine now). Screw the $20, they're just trying to make money off people who are paranoid.

I carry cash ($20 bill, some $1 bills, and change) in a patch kit box. It fits neatly in my seat bag. So my wallet stays home whether I'm riding 25 miles or a century.

I wear "dogtags" engraved with my ICE info. Thought about a bracelet, but since I wear a wristwatch on my left arm and an HRM on the right, I didn't think an additional bracelet would be comfortable.

When I was an EMT I remember hearing that some bicyclists on club rides were encouraged to write their info on the inside of their helmets. My department didn't think that was a good idea, as if a cyclist was injured in a crash it was likely that the helmet would not be removed on-scene unless absolutely necessary to treat an obvious injure, and thus the info would not be found - even if noticed then - until he/she was in the ER. We felt that an ID bracelet or dogtags would be more likely to be discovered during an initial patient assessment right there on the scene.

I would never just rely on a wallet. First off it will take some time for someone to look up your name and address to get a phone number. Someone will have to stop working on you to do that. Second, if your jersey is cut off of you your wallet could be lost in the process.
The Road-id should be a no brainer just as a helmet is a no brainer.

Even if it was down on the patient's feet? That's what I wonder sometimes--whether if I've got a head injury, anyone will notice a little metal tag on my shoe.

Assuming your shoes are still on your feet which is a big assumption.

So we're looking at Road ID tattoos, then...

lol yeah just tattoo your info on your face then they're guaranteed to find it because if you lose your head/face, you're pretty much screwed anyways.