@david wilson: ALARM
The HARM missiles themselves work extremely well for what they are intended; See a target, launch missile, home-in and explode at destination.
The problems re: Serbia were that the "targets" (This is anecdotal from interviews with Serbians on the gound involved in what they determined was resistance to "outside interference". For information peruse some of the military forums such as military.com or fas.org etc.) were very often screened by modified home microwave ovens. Turn on real targeting radar, ping enemy, scare up an incoming bogie which you track. When the bogie gets close to known firing distance shutdown "real" radar and turn on half-dozen false emitters. Result: dead microwave. Cost: $500 tops. Expended HARM. Cost: $317k.
Article here gives some data. Note especially the description of them not knowing friend-from-foe nor hitting the "intended" target.
http://www.fas.org/man/dod-101/sys/smart/agm-88.htm