If you're interested in PEGs, packrat parsers, etc., also check out Roberto Ierusalimschy's LPEG (http://www.inf.puc-rio.br/~roberto/lpeg/lpeg.html). It's a PEG vm for Lua, written in C, and with some tuning for better space performance.

There's an excellent paper about it here -- http://www.inf.puc-rio.br/~roberto/docs/peg.pdf

Similar: http://treetop.rubyforge.org

Topic hijack: Does anyone know of a parser generator lib for javascript? I can't find one on Google.

Answer: http://code.google.com/p/antlr-javascript/

Excellent link. Thanks!