If you think you’re a regex person (not following what XKCD has told us), and that most problems can be solved with simple (yet always too simple) regular expressions, I’ve got a challenge for you: http://regex.alf.nu/.
I know a bit of regexes (use them quite a lot with VI’s search, but it’s not ECMAscript), and I’m stuck at abba. 😀 Gotta study a bit more, or learn how to think again. I could match all the “should not match” words, would be a matter of inverting the match, but I couldn’t find a way to invert the search… thanks, ECMAscript! 🙂
I hope you have better regex mojo, you’ll need it!