In 1920, Congress authorized the Sioux to seek redress by suing the government (which may not be sued except by consent of Congress). The case worked its way through the court system for an incredible 60 years, until damages with full retroactive interest were awarded in 1980. The money has sat in a Bureau of Indian Affairs bank account since then, collecting interest. In 2011 it was worth an estimated one billion dollars. The Sioux refuse to take the money, as that would legally terminate their claim to the Black Hills, which they consider priceless!
Story here on Wikipedia: https://en.wikipedia.org/wiki/United_States_v._Sioux_Nation_of_Indians
Chief Rain-in-the-Face, a Lakota Sioux war chief who fought against General Custer.