I know Shane already posted this in the links thread, but I wanted to plug it more openly:www.texasbighornsociety.org
They do a great amount of work in West Texas restoring the population of Desert Bighorns to their native ranges. The annual work project, which is open to volunteers, is actually this weekend (sorry for the short notice). The work project takes place usually in one of 3 areas: Black Gap, Elephant Mountain, or the Sierra Diablos. Bighorns like high mountains and bluffs (so they can stay away from the lions), and the scenery is always spectacular in each of these mountain areas. Most of the work done involves building and repairing guzzler tanks on the tops of the mountains. See the website for more info.