PBS
Pbs: The Native Americans
The Corps of Discovery came into contact with "Nearly 50 Native American tribes." This site from PBS discusses the tribes that had the most significant interactions with Lewis and Clark.
American Indian Heritage Foundation
Indigenous Peoples' Literature: Chief Joseph (Nez Perce)
This site provides some biographical information about Chief Joseph from several sources as well as information on the Nez Perce. There are quite a few quotes from the great American Indian as well as a link to his famous surrender speech.