The above are just a few of the tools residing in my tool pail, and box. they consist of the following:
Metric box end wrenches. You don't need to get a whole set, most bicycles have 10mm and 15mm nuts, a few older bicycles have an 8mm on the brake cable, and if you have an older bottom bracket you will find a 14mm socket will work on removing the nut.
In the bottom left hand corner are bike specific tools, meaning they are made for working on a bicycle. The top one, with a tail is a bottom bracket wrench, the tail fits into the notches on a lock ring while the box end fits those two sided nuts.
Next down is a 32mm with a 15mm end. Useful for working on headsets and pedal removal(you'll find moset pedals are 15mm). The thin wrench accommodates the tiny room you have to work with, while giving you a big wrench for leverage.
The third is another bottom bracket wrench.
To the right are various wrenches, a spoke driver, along with spoke wrenches, at the top are a bottom bracket splined socket, and a splined socket to remove the lock ring on cassettes.
two sets of allen wrenches complete the ensemble.

Less is more I always say, and in the above picture we've taken out all the unnecessary items and added a couple:
The blue handled whip, is a chain whip, useful in removing cassettes and track gears.
A chain breaker
A Crank puller
and finally two tire removers(usually they come in threes, but I only have two hands).
With these you should be able to handle most repairs and upgrades to most bicycles.

Okay, so you have an idea about the tools you would like to have at home or in the shop, so you can work on your bike. But what about tools that would help repair out on the road.
A handy little pouch that velcros under your saddle, and can carry tire irons, an inner tube, and the folding allen wrench. I like to carry a CO2 tire inflater, and an extra CO2 cartridge. There is also a patch kit, and since this kit resides on my fixed gear, I carry a open end of a 15mm wrench cut to fit the pouch.
On my commuter I like to carry two inner tubes, as I've had the unfortunate experience of flatting front and back. I don't make my repairs to the tube on the road. I'll pack the tube home where I'll patch it.
I don't usually carry the allen wrench, it is useful, only because it is available should you need it. And isn't it an unwritten law of the universe that just when you need a tool, it will be the one you didn't bring along.
For more on patching a tube check out the maintenance page.