GitHub user jehna has fashioned a runaway hit with his unique way of constructing difficult regular expressions.
VerbalExpressions turns the often-obscure-and-tricky-to-type regular expression operators into descriptive, chainable functions. The result of this is quite astounding. Here's the example URL tester from the README:
var tester = VerEx() .startOfLine() .then( "http" ) .maybe( "s" ) .then( "://" ) .maybe( "www." ) .anythingBut( " " ) .endOfLine();
This style may be off-putting to old-school regex pros, but even they would have to admit that it's quite approachable and easy to reason about.
VerbalExpressions has been ported to so many other languages that a GitHub organization was created just to host them all. I think this idea struck a real nerve.