Give all the world leaders a spankin' new computer and put them all in a cybercafe, (oh.. maybe in Korea? Heard they have fantastic cybercafes there), and get them to play a few rounds (heck maybe more than just a few rounds, give 'em the whole day!) of Counter-Strike or Battlefield 1942 or Unreal Tournament. That should ease their bloodlust and allow them to play out their militaristic fantasies without actually getting anyone hurt..

Suggestion to World Leaders