Virtually every piece of science can be used for good or evil. Computers are great, right? Well, the military uses it too. Anatomy and biology is great, right? The military uses that too. Explosive combustion to power cars? Also used to propel bullets. Rockets to explore outer space? Used in ICBMs. Solar lens as an infinite fuel source for astronauts? Death rays aimed from satellites.

Someone invented language a long time ago. The military used that as a tool for communication and more effective killing. Someone invented the concept of numbers and counting. Well, the military uses that too: when we outnumber the enemy 100 to 1, it's a good time to attack.

Some monkey thought the concept of tools would be a good idea. Then monkeys started beating each other on the head with sticks and learned that throwing stones can really hurt.

It becomes too tiresome to worry about the consequence of one's pursuit for knowledge. There's almost always a violent application for everything.

I'd love to be the first person who writes an AI which can pass the Turing test (something many AI researchers associate with writing an AI which is actually self conscious). Imagine the philosophical implications of creating an entity as smart, or smarter, than us! Well, as anyone who's seen any handfull of science fiction movies knows, AI has military applications too.

Imagine if we could find a power source as small as a loaf of bread, but which packed enough power to supply a house for a month. Make it cheap enough, and we could manufacture them as personal power generators for houses in 3rd world countries. Energy compacted that much can also be used to power energy bombs and gauss rifles. Make it cheap, and every soldier can carry one.

Take any computer program (videogames, Microsoft Word, Firefox, WinAmp, whatever you want), and imagine if I figured out a way to make it significantly faster. Probably the algorithms involved can also be used for target-acquisition algorithms, and automated gun sentries.

Peer to peer networks for sharing files? Same concept is used for distributed mine networks in which the mines reposition themselves to increase effectiveness.

Positional projected audio so that two people can sit in the same car listening to two different radio stations at the same time? Used by battleships to send sonic impulses through the ocean to detonate incoming torpedos.