The Voice Keyer is a free Windows based voice keyer. It is very easy to use and it handles up to seven messages. By connecting your computer soundcard to your radio it's possible to just press a button and the computer will CQ for you, to spare your voice. It can also PTT your radio via the LPT port.
Almost all contest softwares have built in voice keyer nowdays so this is something primaly developed for off contest use. That is nothing that limits you though, for using it during a contest. Since I have included keyboard hooking from version 1.5 it can be run in the background and still respond to the F-button. That way you can run it as a normal built-in voice keyer with softwares like CT for windows etc.