[wplug] Emacs Magic

[Joe Gallo]

I'm in the process of switching over to emacs as my editor/operating
system and I'm looking for a Pittsburgh-based emacs guru who can
mentor me in my learning, occasionally answering questions and
providing direction.

At this point, I already know most of the commands that I think I need
to use emacs as an editor; I'm more concerned about the "unknown
unknowns" -- the features of emacs that I don't know to look up on
Google and learn better because they solve a problem I don't even know
I have.

So, emacs-using wpluggers, here's your chance to wow me.  What's your
most favorite "made with secret alien technology" feature of emacs?

Thanks,
Joe