Wrote and illustrated a free online book, later published, which is accessible and somewhat fun/helpful if you don't know much about programming. Wrote some pa

Wrote and illustrated a free online book, later published, which is accessible and somewhat fun/helpful if you don't know much about programming. Wrote some parsers/generators for various markup languages, at least one of which is now part of the Ruby standard library (after extensive rewrites). Kind of like ESR in that he's more accomplished as an advocate than a coder, but unlike ESR doesn't pretend otherwise, and especially unlike ESR had the good sense not to overstay his welcome.