A while ago, while searching Google for Airsoft Maps I stumbled upon the Airbana Airsoft Map, when I found it was sort of still in beta but things are looking pretty good now. As far as implementations of the Google Maps API go, this one is pretty cool.
AirBana's mission is to gather as many playfields and retail locations as possible on their map. It's completely free to use, will integrate with mobile devices, facebook, etc.
I figure some of you out there with playfields or stores might want to make sure you are added to the map. Some of the fields listed aren't even active anymore, so let's get some new info up there! Oregon is looking sparse!
http://www.airsoftmap.us/