Create Zones in Google Maps and Return Zone for supplied city/state

I need a way to visually draw zones on a US based google map. I should be able to zoom in/zoom out while drawing the zones. I want the zones color coded. Zones should be able to be drawn with a pencil type icon (something that allows me to free-draw the zone. Each zone should be assigned a color. The zone will appear as an overlay to a google map and retain it's shape and positioning relative to zooming options. A visual example of the overlay can be found here: <[login to view URL]> Note that I will want many overlays, and the above example shows just one, but visually represents what I want to do. Once the overlays are drawn, I want the ability to supply **something** (like a web service, or other object) the name of a city and a state (inputs). The return value should be the zone number, if available, that the city/state belong to. If the city/state doesn't belong to a zone number, it should return some value letting me know this (for example, 0). Similarly, I may have a zip code without the city/state so I should be able to provide it a zip code instead. OR...if it makes it easier, I can supply the GeoCodes directly and it should return to me the zone that the codes fall within. I have the ability to do it either way, so you do what's easiest for you. The tool provided to do the zone layouts need not be overly complicated or sophisticated. The zones will generally only be setup one time with minor management to change them as necessary. I just need accurate results when trying to figure out which zone a particular location falls within.