Tim Park writes in about TierraWiki, a new project of his that looks slick and sounds promising:

I thought I would write as I am working on a project that blends Google Earth with Wiki technology for outdoor enthusiasts that I thought that might be interesting to your readers. The humble goal of my site, TierraWiki, is to create the most complete reference to the outdoors in existence.

The wiki is based off of the same MediaWiki technology as Wikipedia but I have built extensions to

1. be able to use the GPS track information from our outdoor activities to build a comprehensive trail map that you can access not only on the web but also through Google Maps and Google Earth,
2. enable location based search to make it easier to find outdoors information in the vicinity of another location, and finally
3. have exposed a Google Earth network link that allows you to always have the latest trail map in Google Earth as well as articles that are geotagged.

Basically, I ask that the community go out and use the outdoors on their favorite trails and then upload their GPX tracks to build the trail network. I then have some algorithms that I am working on that can merge this track data, and eventually, will let users plan outdoor trips and have a look at just what they are getting into across the web and Google Earth before they do it (nothing is worse than finding that “extra mountain” on your mountain bike ride).

Here is an example track page, and here is an example of a composite trail map. Finally, here is the TierraWiki network link containing all the trails in its database. Each individual trail is also downloadable as a KML file.

I especially like how it is possible to upload and show elevation and speed data from the GPX file. Wikipedia now has many of its articles georeferenced, but with TierraWiki the geospatial savviness goes the other way — you start with the geospatial data, and then you mark it up semantically with maps, photos and/or a description.

There are of course other good GPS community sites out there, but TierraWiki differentiates itself by using a wiki content model to assimilate information, as opposed to an account/login model. It’ll be interesting to see which proves most popular in the long run.