Great site design. A couple ideas off the top of my head:

- Let hikes to include GPS route(s) to display on the map.

- Link to the USGS topo map that covers a given hike: http://store.usgs.gov/b2c_usgs/usgs/maplocator/(xcm=r3standa...

- Add a bibliography to each hike.

- Scrape some websites to create "stubs" for new hikes and encourage users to develop these.

- Speaking of stubs, if you are going to have collaboratively edited content why not just build on MediaWiki or similar?

- Use OpenStreetMaps instead of GMaps and encourage users to add trails to OSM.