I had to do some plumbing last year on my tankless water heater, but realized that the shutoff valve to my main water line doesn't actually shut all the way off.
I can get it to a slow trickle, but that's the best. I was going to call in the city to shut off the water, but I needed a shower long before the water people from the city would show up so I decided to do the work with the slow trickle.
I know way off topic, but hang in there I'm getting to the best part.
I had to cut out a section of my pipe and replace it with a new one, but as you all know solder and water just don't work so great together.
I did think about the piece of bread, but with the amount of water that I had coming out, I would have had to use a loaf!
So anyway I went over to Ho Depot and picked up some of these quick connectors called Shark Bite http://www.sharkbite.com
I have to say that these things are great, and are still drip free.
You just simply push it onto the pipe and then attach the other side (water dripping and all), and like magic the job is done!