I can't believe I forgot to mention an item of critical importance to any Z Kit: the flashlight. I'd actually put this just after the utility knife in terms of importance, though it could be argued that seeing in the dark is more important than a strong tool/weapon. (I'd disagree.) Let's put it like this: the knife goes in your primary hand, the flashlight in your other hand. That's how important they are.
Naturally, this brings us to the question of "What flashlight should I use?" That's an interesting question, and as always, I have several answers for you.
The first answer is, "Pack two," because certain things are important enough that you should always have a backup. I have a small LED flashlight that I bought at my local grocery store -- and when I say small, I mean it's six inches long -- that lives in the cell phone pocket of my pack. I can get to it quickly, and it's very bright. However, it has two large drawbacks: It uses batteries, and the illumination range of LEDs falls off rapidly.
The second answer, then, is "In addition to having one you can grab quickly, have another that doesn't need batteries." Batteries are like the worst combination of food and ammunition: they go bad after time, they're heavy for their size, often bulky, and if you lose them or their appliance, both are rendered useless. I don't care how butch your D-cell Maglite is, when the batteries run out it's just a heavy aluminum club.
My backup flashlight is the Emergency Pro, because it's also a radio and a cell phone charger. (Actually, with the adapters I have, it also recharges my MP3 player, which is of critical importance to me.) As you may have noticed, I like having tools that perform a variety of functions, because it reduces space and gives me a certain cushion of "overlapping backup", i.e. if I lose my Swiss Army knife, I can still open cans with my hobo tool, etc.
Now let me say this as a warning: I have not used this tool very hard. I don't know how durable it is. It might be a fragile piece of crap. (If so, tell me.) But as of right now, I'm happy with its performance, and I don't plan on testing it to destruction.
So, to summarize, get 2 flashlights. That way you have a regular one which is ready for immediate use, and a crank one for long-term use. And if at all possible, get one that does other things, because that multiplies its usefulness.