| A macro written for the Unix text editor vi. The editor is so powerful that any general computing task can be performed (albeit slowly) by one of its macros; in fact, someone has coded a Turing machine as a vi macro, and I have written a macro which plays Conway's game of life. Slowly.
Those Everythingians who use vi for their writeups might find this macro useful for adding hardlinks:
:map v i[<control-v><escape>Ea]<control-v><escape><enter>
After typing the above from command mode (or doing something equivalent in your .exrc), hit v at the beginning of any word you want to hard-link to painlessly insert square brackets around it. | 
