Repeater Power Point Slide Show - All about what a repeater is, does and why hams use them
http://www.arrl.org/FandES/ead/materials/Repeater.ppt#257,1,Slide 1

Arizona Repeaters - listed by County and Band
http://azrepeaters.net/

Arizona Frequency Coordinators - listing of all repeaters in Arizona
http://www.azfreqcoord.org/

Border Amateur Radio Team - and Repeater System for Southern Arizona
http://www.wd7f.com/bart.htm

Winsystem Repeater System - connecting most of the USA and numerous countries
http://winsystem.org

Eastern Arizona Amateur Repeater Society - also Southern Arizona
http://www.eaars.com/