Okay, so you're sick of hearing me talk about testing. You've been warned
For various reasons, I haven't gotten much done on my current work project. Small database design issues, refactoring, and other considerations have put the brakes on it. I'm building a Web-based inventory control system and for four days, I didn't not fire up my browser once. I relied exclusively on my passing tests (over 700 at this point) to ensure that the stuff worked. After those four days and much effort, I had redesigned much of the code, refactored out more than I thought I could and restructured parts of the database. I fired up my browser, logged in, and everything just worked. Four days, many CVS commits and massive work on a system and it performed flawlessly -- without my ever having run the application during that time. Humbling.