Windows only: ControlPad is a lightweight application launcher that uses the number pad on your keyboard as a quick launcher for applications and system commands.
Once you've downloaded the portable version or installed ControlPad you can access the quick launch dialogue box, as seen here, by pressing the * key on your number pad. The box pops up and you key in a string of numbers that have been linked to the effect you want—bonus points for anyone who guesses what we linked 2112 to in our test of the software.
Not so keen on usiing numbers to launch your applications? Not a problem—you can just as easily use words if you want. You can press and hold the * for longer than you would to just call up the launcher and it will enter into editing mode. Enter a new command and hit the / button on the number pad to associate it with a new launch code. You can also bulk add new launch codes by opening up the commands.ini file, and there are several examples in there to show you the syntax.
ControlPad is free, Windows only, and available as a portable application.