For newcomers, C-g is a delight (it certainly was for me). Especially with the arcane reputation of Emacs, it was awfully reassuring to know how to get out of whatever unfamiliar function I'd fat-fingered myself into.
Well, it won't get you out of recursive edits. I remember visiting a coworker's machine before telling him about those, and the modeline was something like [[[[[[[[[[(CPerl)]]]]]]]]]].
ESC ESC ESC is a much better "get me out of here!" command to remember.
