Sizzling Keys is a free application for Mac OS X that allows you to assign hot keys for use with iTunes. But you can already do that, right? Well, if you switch out of iTunes then the hot keys don’t work. But with Sizzling you can have keystrokes that work to control the basic features of iTunes no matter what application you are in. I have not found an exact equivalent for Windows, although if you click on the Advanced tab of the iTunes preferences for Windows you’ll see the Show iTunes icon in System Tray, which will place it down in the lower right hand corner of your screen.…