I'm a total tool nut. There's times I'm at the store, and I don't ask IF I have that tool, I ask if I need ANOTHER of that tool.

Over time, I've broken pretty much every tool made, and I've learned to buy a bit more carefully. While Mac and SK tools are fantastic, I don't think it's realistic for everyone to be able to afford a kit like those.

That said, I've found that there are some ready-made kits that are fantastic starter tool kits. In particular, I picked up a kit from Home Depot that has been really useful, in a lot of ways.

It's this this kit from Home Depot.. Now this kit is missing a few important things, specifically tools for cutting, boring and measuring, so to this kit I'd add a cordless drill that uses an 18v or greater battery, a set of twist and spade drill bits from 1/16 to 1 1/2" by 16ths up to 1/2" and by 1/8" over 1/2".
I like Pull Saws, they are compact and cut well.
A good hacksaw and a set of blades is a must.
For measuring, the tool kit has a decent 25' tape measure, but a Try Square (6") would be a useful addition.

A good, stout prybar can get you out of a lot of problems.

Finally, you'll want a decent flashlight and a bin of fasteners - drywall screws from 1" to 2 1/2", some nails, some machine screws.

Soldering torch

The one thing that didn't appear on anyone's list is probably the most used plumbing tool in existence...

The Plunger or plumber's helper or whatever clever name you call it.

I can hammer a nail with a rock.
Maybe, drive a screw with a coin.
But, there is no way I am going to use my hand to unstop a plugged up toilet!

+5!! Way to go porkchop...

Maybe it's too late, but during the holidays, Home Depot had some sets of tools for really cheap. I don't know quality and I don't know what's needed either, but maybe they still have some left over.

Eye and ear protection, gloves, FAK, work books, and other protective gear

Another list with some justification.

http://moljinar.com/page6/files/Disaster%20Cleanup%20Tools.pdf

Many good suggestions already made, to which I would add, not just a toilet plunger as has just been suggested, but a full set of drain rods including a rubber disc for clearing toilets.
Most toilets plungers have rather short handles, but use of a drain rod keeps ones hand further away from the waste.

With suitable brushes, drain rods can also be used for sweeping most types of flue or chimney.
Also useful for prodding and poking anything that you don't want to touch.

In addition, do not forget plenty of spares or duplicates of items liable to wear or breakage, saw blades and drill bits in particular. And small items vulnerable to loss.
Several small and reasonably cheap pocket knives are useful, in an emergency it is surprisingly easy to loose them.
Many members of these forums probably replace or upgrade pocket knives when a better model is available, don't forget to put the old ones in your emergency tool kit.