Easy: G15 Keyboard, however its not free.
Decent & Free: AutoIt (
Link) Software & Below Script.
(!empty($user->lang['CODE'])) ? $user->lang['CODE'] : ucwords(strtolower(str_replace('_', ' ', 'CODE'))):
HotKeySet("{Home}","click")
Hotkeyset("{END}","stop")
Hotkeyset("{PAUSE}","Pause")
Global $Paused
Global $Wait
Wait()
Func click()
While 1
MouseClick("left")
sleep(100)
WEnd
EndFunc
Func Pause()
$Paused = NOT $Paused
While $Paused
ToolTip("Paused", 2, 0)
Sleep (400)
WEnd
EndFunc
Func Wait()
$Wait = NOT $Wait
While $Wait
ToolTip("Press the HOME key to start ", 2, 0)
Sleep (400)
WEnd
EndFunc
Func stop()
Exit
EndFunc
Run the Script with Autoit, Home starts clicking, Pause obvously pauses, End closes the script.