VoiceAttack - VoiceAttack will take commands that you speak into your microphone
VoiceBot - Take command of your games with your voice using VoiceBot!
VoiceMacro - Control applications or games by voice commands and/or by the press of a keyboard, mouse button or...
GAVPI - GAVPI is an open source voice command software / speech recognition key bind tool.
VoxCommando - VoxCommando is a speech recognition and command utility for Windows. Perfect for HTPC control and home automation.
Work by Speech - Work by Speech is the first program in the world that allows efficient work on a computer by speech without needing a keyboard and mouse.