This may have already been posted here, but someone on my friendlist posted this link. It's a discussion of how long it would be before power stations would run down in a Dawn Of The Dead scenario. If it has been posted before I'll be happy to remove this post.
I haven't the faintest clue how to look this one up. A previous post mentioned opiates and, er, v-something (the appropriate tags are down, if the post was tagged) as sedatives that would be available in medieval(ish) times, but what would be the tech-level-appropriate way to actually give opiates (or whatever would be likeliest, though opiates have the advantage of a recognizable common name associated with 'em) to a patient about to be operated upon? Tea? Alcohol extract? Swallowed whole as a powder/paste/pill? Chewing on the appropriate plant part? (and, if anyone happens to have the url of that earlier post, the one about amputating wings, handy, then bonus...)