I'm sure some of you know this already, but I thought I'd post this for everyone else.
iTunes has a handy feature that allows you to freely create and switch between iTunes libraries.
On a Mac, just hold the option key down while launching iTunes, continue holding the option key down during launch until you are presented with the dialog box to create or choose an iTunes library. For Windows, press and hold the shift key down instead.
This is really handy if you want to keep your works-in-progress rough mixes separate from your iTunes library of commercially released music.
I know myself, even with all the view and sorting options in iTunes, it gets to be a hassle to track down and delete rough mix tracks within my regular listening library. Having a separate rough mix library makes this much easier and quicker.
Paul