iTunes: What is the usefulness of checked/unchecked songs? I know the functional effect of unchecking a song: it doesn't play (except when explicitly double-clicked) and doesn't sync with an iPod/iPad. But how is this useful? Does Apple officially recommend any sort of usage of the checkboxes? Or, more subjectively, do you make use of the checkboxes in iTunes, and if so, what songs do you check or uncheck and why?
It keeps holiday music out of my playlists, off my iPhone, until I want to overdose on them from December 24th through 25th every year.

For that alone: I love the check box.