A long time ago I ran across mention of an editor as a perl one-liner. (It may have been here-I honestly can't recall.) The code went (line broken for readability here):

perl -MTk -MTk::TextUndo \
  -e "(tkinit)->Scrolled('TextUndo')->pack; MainLoop"
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(By the way, if anyone might know the original attribution for that bit of code, please let me know-I've found it quite useful from time to time, and would love to direct credit where it is due.)

Update: (21 Jun 2006) A trip to the a good search managed to find a mention of the code above dating from a 2002 thread on editing large text files, which could very well have been where I might have first encountered it.