Difficulty is in the eye of the beholder: A green at Jackson Hole is a double black in the Midwest. Rather than taking the resort's word for it, Dallas developer Dale Greer took publicly available GIS data and mapped the slopes dozens of resorts. Steepness is color-coded the same from map to map, with yellow representing expert slopes with an
angle in the neighborhood of 40 to 50 degrees down to lime green for beginner runs with a pitch below 10 degrees.
The end result is a relative scale for comparing the terrain at resorts from Colorado (the site has maps of nine of the state's resorts) to Kazakhstan. Greer also sells some CafePress shirts and posters bearing his mildly psychedelic maps. Coolest of all, download the Google Earth plugin and you can sail above the virtual 3-D Rockies and swoop into resort after resort for a better view of its color-coded overlay.