Native American Tribes have ballot initiative rights. In Arizona, the Navajo Nation has Initiative Rights that can be used to deal with problems affecting the environment and social justice.
According to Ballotpedia, in 2009 an initiative was launched called the Tribal Reduction Act and this shows that the possibility for more radical proposals to help their nation can be proposed and put forward on their ballots.
According to the Ballotpedia link the Tribe needs 15% of the 110,000+ registered voters to get initiatives on the ballot.
This process can be used to deal with issues affecting all people in Arizona such as, Uranium mining that attributes to high cancer rates and the threats of Fracking. It can also be used for Native specific issues that would be decided by the tribal members themselves. Naturally, the first additional purposes of using this process could be for expanding upon the current direct democracy rights on native land and adding the right to citizen grand jury, recall and stronger voting rights for the people.