ProPeru (Apartado 70, tel. 084/20-1562, www.myproworld.org [1]) is a highly recommended organization, run by a Peruvian named Richard Webb. The organization arranges homestays for college students (and older folks, too) in Urubamba [2], Cusco [3], and other areas in Peru [4].
Students take classes in art, history, anthropology, and Spanish, and work on service projects that range from reforestation to setting up a women’s shelter or the town’s first Internet café. ProPeru receives rave reviews from its students and is surely one of the better foreign study programs in Peru.
Other volunteer organizations in Urubamba include Casa de los Milagros (casademilagros [at] yahoo [dot] com, www.chandlersky.org [5], U.S. tel. 408/532-0644), which works with children with disabilities.
Links:
[1] http://www.myproworld.org
[2] http://www.moon.com/destinations/peru/the-sacred-valley/urubamba
[3] http://www.moon.com/destinations/peru/cusco
[4] http://www.moon.com/destinations/peru/discover-peru
[5] http://www.chandlersky.org