The Army has traditionally named helicopters after American Indian tribes. Off hand I can think of Iroquois, Chinook, Kiowa, and Apache. Some exceptions would be the Cobra, Skycrane and Little Bird. Even some munitions are named after American Indian tribes, such as the Zuni rocket.
NOTR reports that the new armed reconnaissance helicopter is slated to be named Arapaho, and makes an amusing (and, in my opinion, entirely accurate) observation on what the troops will likely refer to it as.