My colleague, Chris Haller, has done some great research on online mapping tools/techniques that can be used for community planning and community building. Here's some stuff he discovered on GeoTagging.
Since Google started its mapping service, based on xml and an API open to everyone, a lot of non-affiliated web applications have been emerging that bring GIS and online mapping closer to “Joe Internetuser”.
A short look at the emerging world of “map hacking”
In the meantime a lot of web services have been developed, taking advantage of these possibilities.
As a result of enabling tags with spatial references, geotagged pictures hosted at flickr are shown on a google map of the united states at geobloggers.com. http://www.geobloggers.com/
MyGMaps.com lets users create, save and host their personal maps by simply filling out a form. http://mygmaps.com/mygmaps.cgi/
Foundcity enables members to send photos and text messages from the street to a personal map: http://www.foundcity.net
An even more impressive application is the linkage of housing offers on craigslist with google maps: http://www.housingmaps.com/
The amazing result of this movement is that online mapping finally leaves the stage of a small group of experts and hits a broader audience of web users . . . unless of course Google decides to redefine the licensing arrangements for distributing the data.