Mellis, I was going to point someone to the [u]switch tutorial[/u] in the playground , but I found that tutorial really confusing.
The first problem is that the wiring diagram is confusing. Its unclear which pins the wires go to on the arduino and it's not very clear what that resistor is connected to.
And it looks from the diagram like the pin would be normally high, pulled low when pressed but the text says the opposite happens.
Another issue may just be with choice of example. I think it would be difficult for the target audience to figure out how to do a non toggling version from the example code. A simple debounce of on and off would probably be used at least as much as a toggle.