That's a good point - words/min isn't a great way to measure code typing speed. Right now I use whitespaces to delimit "words" - maybe I should also delimit by parentheses and punctuation? e.g. "Object.create(http.IncomingMessage.prototype)" is a very long word :D
Not sure whether there is any standardized way to measure words in programming languages. The natural unit would be tokens, but these are even more language dependend than words of a natural language. Chars/minute makes more sense.