If you're an addon developer, get
zgoo. It's essential. Helper functions are under "zo_Helper" when you run /zgoo
Additionally, that globals wiki page is good. I cross-reference between the two constantly when developing.
Edit - while on the topic, what would be really useful is a wiki page of a globals dump that goes down 2 or 3 levels. e.g. If there is a table, expand the table down 2 or 3 levels.
I've tried to obtain this information recursively using "for x, y in pairs(_G)" but the "private function" errors are blocking.