Every now and then a really cool site catches my eye.
Gutsploder.com are a couple of dudes, riding trails armed with a camera and a GPS (Global Positioning System) in order to make detailed maps of various trails. At many points along the trail, they mark a GPS waypoint, take photos of that part of the trail, and later produce a detailed map with markers and photo links for those locations.
The results you can check out at
www.gutsploder.com(Only a couple of maps right now, but imagine if every trail was marked like this)