I’ve been looking for list of types of queries that geocoder supports beyond regular address geocoding. At this time I need to query Google for airport locations.
I have stumbled upon this IBM document but it mentions no place where I can get up-to-date list of allowed and useful Google geocoder query parameters.
Also look at the Yahoo APIs. I tend to find them a bit more hacker-friendly than Google’s APIs. Specifically, look at http://developer.yahoo.com/maps/rest/V1/geocode.html for geocoding with Yahoo.