Find a [whatever] near you with Rails and the Google Map

Has anyone built a “Find a Physician” or “Find a Dealer” or whatever
using Rails and the Google Maps api? I’ve found a large number of
tutorials ca. 1996/7 and one seemingly current project on Github for a
general-purpose Google Maps connector gem, but I’m hoping to find some
tips about using the map to find the nearest physician’s practice to the
customer’s Zip code. There would be a few hundred practice locations,
all in upstate NY, if that makes any difference.

I’m very familiar with doing this in the traditional Great Circle
calculation, but I was interested in learning a new trick – how to do
this with the Google Map – seeing as that might be more accurate in a
sparsely populated area.

Thanks in advance,