Isn't the section on non-lethal damage what you are looking for? I think the rules cover it pretty decently. The average person only has a few HP, so a non-lethal strike by even a fairly low-level character would drop them pretty quickly. Take your average martial arts flick. The big hero is taking on the horde of wanna be's. They would be like 1st lvl. char. and if you put the hero at around 10th, he'll be dropping them like flies. Now, if you mean dropping really high level characters with a single blow, that's a little harder. But in most movies and fantasy stories, how often do you see the main heroes or villains being taken out in one shot? It's usually some big epic fight where each side lands a ton of shots that would kill the average person. It seems to me that this is what D&D is trying to emulate. If you were to equate your encounters to be like the movies or fiction novels, most of your players would be taking on a lot of creatures and NPC's that they can just mow through, with only a few tough battles before the big showdown. Most DM's (myself included to a point) game differently, throwing much more challenging encounters on the average than the average action hero sees. I, like some DM's, prefer my worlds to be very random so that my players get more easy encounters than the DMG suggests, but I always worry about boring the players. So, I usually end up trying to balance it out at some point.
The bigger the discrepancy between your players' characters and their foes, the easier it is to get those "1 punch knockouts" like you see in the movies. Like I've heard other DM's say, "When in doubt, throw the CR out". If you want to have those kinds of encounters for your players, put them in there and don't worry about the CR or EL. But I think Ilamatron2000 makes a good point about balance. D&D has seemed to make it fairly difficult for evenly matched foes to just knock each other out. But I've had players run even low level Rogues who could sneak up on guards and knock them out with a single blow. Even taking the Jack Sparrow example, using surprise and having a little skill with the bar to take the -4 to deliver non-lethal would still give someone a pretty decent chance of knocking someone out with a single blow.
One other thing I try to remember is that movie physics don't really model real physics very well. I have some friends who run an SCA style combat group called "The Horde". These guys beat each other with sticks basically. I've seen guys take really hard shots with rattan swords and not get knocked out. Sure, they got their bell rung, but they didn't get knocked out. I was in a bar fight in Milwaukee once where I saw a guy get hit upside the head with the fat end of a pool cue and he didn't go down. My former instructor, Pet Hetrick, is an escrima fighting national champion, and I've watched those guys spar. And shots that I was sure would knock someone out (accidental shots during training), didn't.
A lot of things that would normally happen in the real world don't have a chance of happening to a bunch of high level, high magic characters. It sounds like you might like a little grittier version of D&D than core, and there are tons of variants (some even in the DMG) that can make combat much more deadly and unpredictable. Take the Defense Opposed Roll, for example. By having the defender roll for their defense, not only does it add randomness to the fight, but a low roll makes them much more susceptible to a critical injury. Add the Clobbered Variant, which makes a creature that takes 1/2 its current HP restricted to a standard action the next round, which kind of emulates them getting their bell rung. Throw in an Armor as DR variant which makes people a little easier to hit (unless you balance it with a Class Defense Bonus) and people can start dropping like flies. The thing to remember is that the rules work both ways. Anything you do to make the combat grittier and more dangerous will affect your players' characters as much if not more than your monsters and NPC's. My players love a super gritty, low magic, "it's me not my gear" kind of campaign so we have plenty of knockouts and quick kills. One shot knockout outs are there, but you definitely need to coax your game a little to make them more frequent than Core would allow.
