The U.S. Navy (in support of the Marine Corps) has deployed an unmanned cargo helicopter called K-MAX in Afghanistan where it has worked well. Since they helicopter doesn't put flight crews at risk, it can operate in weather conditions where the military wouldn't ordinarily have risked flying for a mere cargo mission and it has had little downtime.
Also, unlike many military technologies, Lockheed's K-MAX helicopter has obvious cross-over potential in civilian applications.
Lockheed has also successfully tested a system that uses lasers to wirelessly recharge the two hour life batteries on a small unarmed electrically powered UAV with a three pound payload while it is flying. In a flight test, Lockheed was able to keep the drone aloft for 48 hours, in admittedly optimal indoor conditions.
The U.S. Navy is also at an advanced state in using drone helicopters (the Fire Scout) in roles similar to a (sometimes) armed reconnaisance helicopter.
And, the Navy is in an advanced prototype stage of the development of a carrier based drone stealth fighter with both Boeing and Northrop Grumman having advanced prototypes in contention for a weapons system that is supposed to enter service in the U.S. Navy six years from now, in 2018. Adapting such a drone to the less specialized requirements of deployment from ordinary runaways for the Air Force would presumably be a trivial modification of the technology.
One of the primary ethical issues that is emerging as armed drones develop is serious skepticism about the extent to which their strikes are causing civilian casualties in places like the CIA prosecuted drone strikes in Northern Pakistan intended to target Taliban forces that have taken refuge there from their former base of operations in Afghanistan.
Meanwhile, the U.S. military's top of the line (and extraordinarily expensive) manned Air Force fighter, the F-22, has been having serious problems with a system unique to human piloted craft, its oxygen systems, that have cost several planes and some pilot lives.