I'm a big fan of BigPictureSmallOffice, mostly because I don't work in one anymore! Apparently the IT department managed to entirely bork the company's database, including the list of oustanding orders. Yee Haa!
Hey, I've been there. One month into starting my first job I deleted a live customer website. Now, we were transfering it to a new server and there was a new design, so no permanent harm done. But the old site was still live (or rather, recently deceased after my act of vandalism), and due to the vagaries of DNS updates, still needed to be live for at least a week. Oh Joy. Let's just say that the client's ISP still had the old IP, and the client was having a hard time believing that other people could see their new site even though they couldn't.
Never make the same mistake twice. Well I have never deleted a live website since. You might think the lesson I learned was: always check twice. Oh no. The lesson I learned was: if you mess up a client and your boss has to handle the angry phone call because you were late in that morning, you are in deep deep doodaa.