added:
An editor that started out as a set of macros for the [TECO] editor. It has since grown into an editor in its own right.

"X is actually EMACS on acid." - (c) 1994 Stephen Kelley 

An Emacs reference mug is what I want.  It would hold ten gallons of coffee. - Steve !VanDevender 

Emacs has also evolved to break more standards in more ways than any other  non-Microsoft program I can think of; it's held together with spit, duct tape, and collusion against defenseless compiler vendors.  - Peter Seebach (1999)

If you have Emacs, what do you need an OS for? - Alistair J. R. Young  (1998)

You see, it's really true: all UI's will become Emacs with the passage of time... - Charles Shannon Hendrix (January 2002)

"Emacs is a nice operating system, but Linux has a better editor." -Neil Schneider