I believe that ExtremeProgramming has to do with taking your PowerBook rock-climbing. Or maybe it should be called EffectiveProgramming instead :) -- RobRix

See The PortlandPatternRepository is where most discussion regarding XP, as it is called, takes place. KentBeck and RonJeffries, while working on ChryslerComprehensiveCompensation(or C3), invented this particular methodology. ExtremeProgramming emphasises:

UnitTest ReFactoring YouArentGonnaNeedIt OnceAndOnlyOnce OptimizeLater ContinuousIntegration *TheSimplestThingThatCouldPossiblyWork