Got an unstable application that you can't give up for whatever reason that also freezes up on you regularly? Weblog CyerNet details how to create quick-kill shortcuts for specific applications using either the built-in Windows command line tool taskkill, or a third-party command line tool called taskill (notice one less 'k'). With the default taskkill, just create a shortcut that runs the following:
taskkill /f /im firefox.exe
Where firefox.exe is replaced by the the application you want to force to quit. Lastly, if you're a *nix user (Mac or Linux), you can use the killall command, so a similar command would look something like
killall firefox-bin, though you can dig deeper when killing apps on your Mac if you want.