You can buy a number of programs to control your computer by speaking to it. Star trek style. Awesome. I'm told Windows 7 even includes one standard, one capable of arbitrary dictation, so you can write out your entire thesis by speaking into notepad.
This is not perfect, such programs are easily confused by words that sound close to alike, but I wanted to try it for myself, so I installed a program called CVoiceControl, and began to work it.
First, it requires microphone calibration. A program tells you to record silence, speaking, screaming, and other things until it's confident in the way that the microphone works.
Then, it requires you to train it. You enter a command for it to register, like "firefox," and then you record something to activate it, like "I want to surf the web." The longer the better, the instructions say. You need at least four recordings of yourself, and the more the better.
Then, it's testing time. When it came time for me to test, I could not get it to trigger. I think I messed up on the microphone stage or something. It just couldn't figure out what I was saying.