Web page to find the center of a bunch of addresses.
This was my first learning experiment with the Google Maps API, but it turned out to be popular/useful enough to keep around, and do assorted little improvements on.
It works by first retrieving the latitude and longitude of each address you enter, and then simply averaging all the latitudes and all the longitudes. Then it puts a marker at that point, plus all the addresses, and makes sure it's zoomed out far enough that they're all visible.
There is a live copy at:
If you copy this, please use your OWN Google API key, rather than running up my request count!