The Cherokee Nation maintains an informative website with a history page containing short essays, biographies of important figures, and numerous documents.
Public historian Barbara Landis had constructed a useful site on the Carlisle Industrial Indian School. Photographs, a virtual tour of the school grounds, extracts from the school newsletter, and a bibliography are available.
Several resources useful to teaching and studying the Ghost Dance, including a brief 1894 film and eyewitness accounts, are made available by "Teaching American History in Maryland."
Links to essays and documents relating to the history of the Indians of the Black Hills from the Treaty of Fort Laramie to Wounded Knee are available here.
Almost 200 photographs are made available here by the National Archive.
A huge collection of photographs has been posted by the Library of Congress.