Hello,
Google offers an open API for displaying custom information on their
highly usable map application. This API seems suitable for wikis,
which is why there are already three MediaWiki extensions for Google
Maps. But these extensions seemed a bit too rigid for me, needing
database modifications and RSS feeds and the like just to display
markers. So I wrote a simple Google Maps extension: to create a map
with many labeled markers, you just describe one marker per line with
the format "latitude,longitude,label", and put all of these markers
inside of a <googlemap> tag. A neat feature is that the marker labels
will render wiki formatting. Because of its flexibility, I think this
extension will prove useful in a wide variety of projects; I
encourage you to try it out and send me feedback.
http://meta.wikimedia.org/wiki/User:Emiller/GoogleMapsExtension
Evan Miller