My hope for the future, as far as military technology goes, is that as our science gets better, our weapons will become ever more efficient -- and less lethal. After all, if you could easily disable and subdue an enemy without killing him, wouldn't you? It's war without the nightmarish moral quandaries.
At least, that's the theory -- although in practice, it hasn't always worked out that way. (There were more than a few times in Vietnam where American soldiers used tear gas to flush VietCong from tunnels, only to mow them down; the fear is that the result would be similar with weapons like aerosolized Valium [nixed by the Pentagon for moral reasons, if you can believe it] or any of the weapons described below.) I guess it's just like Spiderman says: with really cool weapons comes great responsibility.
The gay bomb
The winner of this year's Ig Nobel prize for ridiculous scientific achievement went to the Wright Laboratory of Ohio, which developed the idea of an aphrodisiac bomb which would inspire "completely distasteful but non-lethal" homosexual behavior, distracting enemy troops with one another. Brilliant, yes, but sadly lacking in specifics -- would the effects be immediate? How quickly would they wear off, if ever? Would it turn already-homosexual troops straight? So many questions, so few answers. (That's the problem with hypothetical weapons.)
The Silent Guardian
Developed by the Raytheon Corporation, this "gun" fires off high-intensity beams of radiation for up to 500 meters, and anyone in its path will be overwhelmed by a nasty burning sensation. It's kind of like a big microwave oven with the door taken off -- except the wavelength of its beam is much shorter, so instead of cooking you all the way through, its heat only penetrates your flesh for about a tenth of a centimeter, which Raytheon says isn't enough to hurt you permanently, just make you scream a lot. Critics point out that the beam is only non-lethal when used correctly -- but if left on for just ten seconds, it can reach temperatures of up to 80 degrees Celsius; more than enough to give its target second- or third-degree burns, which can be life-threatening.
Long-Range Acoustic Device
Sonic weapons are just coming into vogue, and are pretty nonlethal, but not always. Take, for instance, the anti-frogman bursts of sonar that can be emitted by some military ships; it's so powerful that it can kill the frogmen in question rather than just repel them, as well as ruining the collective day of local aquatic life. (A series of high-profile blue whale beachings in Southern California recently have people wondering if they're not being confused by Navy sonar weapon tests.) The LRAD in question, however, is used for land-based crowd control. It emits a sound 50 times louder than the human ear's pain threshold, which can permanently damage hearing. So far, the device has seen action in Iraq, during protests at the 2004 Republican National Convention in New York, and on a cruise ship to repel Somali pirate attacks. Then, of course, there's the hypothetical-but-hilarious brown note weapon.