Tonight I got this zombie dialog box:
The OK button is not clickable, and clicking the box does not bring it to the front. I believe it came from a SuperDuper! glitch, but if it's attached to a process at all, the process is called neither "Copy Job" nor "SuperDuper!". So I have no way of getting rid of it other than logging out and back in.
Back when I was a Windows user, I used a Sysinternals app called Process Explorer that let me basically click on a window to see exactly which process it belonged to. Is there a utility for OS X that does something similar?