Just a quick note on "mission critical." I've always found that to be an interesting term. I'd argue that software components critical to your business are mission critical, practically by definition. It doesn't matter if I'm an old-school avionics company or a Web 2.0 social bookmarking site . . . my software is mission critical to my business.
I second that. If you have something like a display bug or some strange inconsistency in a website, having that bug there is actually a chance for you to show how responsive you can be to user bug requests. That is, having and quickly fixing a bug could turn out to be a good thing. That is not the case if you are NASA or your local nuclear power plant.
