An App that your using Freezes, and your first thought it to CTRL+ALT+DEL to bring up Task manager, then you have to wade thought the processes to find said frozen app, then kill it... Or you use xKill. Using a system wide hook in xKill, when it is running, just Press Control+Alt+Backspace, and you will see a Skull and Crossbones follow behind your cursor. When you click on the next item (say, the frozen application), it will kill it. simple.