The US military has had "directed energy" technology available for years, but getting it into the form of a battlefield-practical weapon is taking longer than hoped. Some directed energy weapons act much like phasers from Star Trek -- they have a range of settings from "annoy" to "stun" to "lethal" that hit the target at the speed of light and can be easily redirected and refocused. Certain frequencies can even travel through walls. Couple that with heat-sensing technology that lets you "see" through walls, and you'd be able to immobilize every person in a room before entering -- something soldiers could definitely use on raids.

Certain forms of directed energy weapons are already in use in places like Iraq. A hand-held laser that temporarily blinds a target by filling their field of vision with bright light is already used at checkpoints and roadblocks. These low-power lasers do no permanent damage. Other weapons in development send pulses that disable land mines and vehicles without physically destroying them.

Other energy weapons being developed are on a much larger, much more damaging scale:

The main problem with deployment of these weapons is making them small enough to transport easily, and, of course, powering them.

I think it would be great if soldiers could stun or otherwise disable potential enemies using a targeted beam, and without using current chemical or projectile weapons that can cause serious and permanent harm.