Search with http://www.searchtofight.org, and Yahoo! will contribute a significant portion of its advertising revenue generated by your clicks on paid advertising sites to the American Cancer Society.
SearchToFight.org  is the first search engine to benefit only one nonprofit organization. While there are other search engines that allow users to choose a nonprofit to which direct funds raised by their search activity are allocated, SearchToFight.org exclusively benefits the American Cancer Society's efforts to fight cancer by funding cancer research, providing prevention and early detection information, advocating for all people to have access to screening and treatment, and offering free programs and services that improve the quality of life for patients and their families.