The trend in air-launched missiles, especially those used by UAVs, is towards smaller and lighter. The latest example is the STM (Small Tactical Missile), a 6 kg (13 pound), 600mm (24 inch) long and 100mm (4 inch) diameter, laser guided weapon. STM is basically a smaller version of the 15.6 kg (34.5 pound) Griffin, which recently entered service in Afghanistan.
Smaller air-to-ground missiles enable targets to be destroyed with less risk to nearby civilians, and friendly troops. All these are alternatives to the Hellfire II, which weighs 48.2 kg (106 pounds), carries a 9 kg (20 pound) warhead and has a range of 8,000 meters. The Griffin has a 5.9 kg (13 pound) warhead which is larger, in proportion to its size, than the one carried by the larger Hellfire missile. Griffin has pop-out wings, allowing it to glide, and thus has a longer range (15 kilometers) than Hellfire. UAVs can carry more of the smaller missiles, typically two of them in place of one Hellfire. There are similar arrangements for Griffin.
Currently, there even smaller options, like the guided version of the 70mm air-to-ground rocket. These are 11.4 kg (25 pound) missiles, with a laser seeker, a 2.7 kg (six pound) warhead and a range of about six kilometers. The 70mm missile is designed to be carried in a launch rack that replaces the one used by Hellfire, but carries four 70mm missiles for each Hellfire. Now there is the STM, which is small enough to be carried by smaller UAVs that cannot carry the 70mm missiles. With a range of only a few kilometers and a one kilogram (one pound) warhead, STM has enough bang to destroy a vehicle or a room in a building. With its laser guidance, that's enough for many targets.