While in use by the Air Force, the E-3 is far from the only plane to wear the AWACS designator. The other well-known entry is the US Navy's carrier-borne E-2 Hawkeye, a propeller-driven stalwart that's been launching itself off the Navy's flattops since Lyndon Johnson sat in the White House. Both the E-2 and E-3 serve as battlefield coordinators for both land- and sea-based aircraft in a war theater.
The E-8 Joint STARS, meanwhile, could be thought of as AWACS for ground forces. Short for Joint Surveillance Target Attack Radar System, the JSTARS is, like the E-3, based on a modified Boeing 707. It uses a variety of electronic systems to monitor ground activity, and can deliver vectoring and other intelligence to both land and air forces.