While helping out on a project, I ran a few unit tests. When it ran, my collegue remarked, "There's the letter coming out of the printer now". I was a bit surprised and asked if there was a config setting to prevent it from printing everytime i ran the tests. Unfortunaly no was the answer.
So in an effort to not kill as many trees I downloaded CUTEPDF which is a program that allows you to use it as a printer but saves the output to a pdf file. I changed all the printer references in the tests to point to the newly installed "printer" and whoolaa...no more trees being kill, and tests still run fine.
There's a few other programs out there that are similar, I've used CutePDF a few times now when i'm doing development and process testing. I find it great when your building reports/generating files that need to be printed but you don't actually want to waste paper until you think you have it "just right".