What is the output of testing? Since I believe testing is the act of providing information about the system under test, then the answer is 'Information'. This information can be imparted several ways, the most notable of which is a bug report. It is not the only avenue, nor is it the only information that testers gather. However, I do find that is seems to be the only information that is requested/expected from other project members. If they are only interested in bug reports, this leads to holes in the stakeholders understanding of the system. But what do you do when the people you are supposed to provide information to, do not tell you what information they require?
Leading on from this is the idea that the only time we can give useful information is during the system testing phase of a project. However, many times I have discovered issues with the design of an application that would have been recitfied mcuh earlier if only I was involved with the design phase. What is particularly annoying though, is that in numerous project reviews, it is stated that testers should be invovled earlier, and it is always forgotten/ignored for the next project. And so the cycle continues.