Geez, Norm, if your Arc bounces onto the tracks and stays lit, you can easily find it, and if it turns off, just pull out another light to find it with!
Actually I was just thinking about that story in the context of wondering how much battery runtime you'd need in that situation. I figure the subway stations are maybe a mile apart, which means a 1/2 mile walk at most, so 1/2 hour of light should be enough. That makes the Nano-Illuminator (Arcmania and Lambda's new N-cell Luxeon collaboration) probably up to the job.
As for giving away lights, I've been giving out those $1.00 Countycomm keychain lights and they've been appreciated. They would have worked fine for that subway thing, if enough people had them (one of them is not really enough to light the way for a large group). I think I'm about out of them and will probably buy another 20 of them. The Princeton Tec Blast is also a great gift light. It's cheap ($6.50 at TTS including batteries), brighter than a Minimag, and is very light and small (Arc LS sized, 1.5 oz, uses two AAA's).
Right now I have an Arc AAA and two Photon II's on one keychain (to lose all at once, heh) but I don't always carry that keychain. On a smaller keychain I have an Arc LS (and fewer keys) and I have that chain when I don't have the bigger one.
I remember hearing something about a wristwatch with a bright 3mm LED flashlight built in. That might not have such good runtime, but it would be pretty hard to lose.