Anytime you're using the iPod Touch for music, whether you're playing songs or just flipping through your lists, you can rotate the Touch 90 degrees in either direction—so it's in landscape orientation—to turn on Cover Flow. Nothing gets oohs and ahhhs from the admiring crowd like Cover Flow.
In Cover Flow, the screen goes dark for a moment—and then it reappears, showing two-inch-tall album covers, floating on a black background. Push or flick with your fingers to make them fly and flip over in 3-D space, as though they're CDs in a record-store rack (remember those?).
If you tap one (or tap the little button in the lower-right corner), the album flips around so you can see the "back" of it, containing a list of songs from that album. Tap a song to start playing it; tap the in the lower-left corner to pause. Tap the back (or the button) again to flip the album cover back to the front and continue browsing.
To turn off Cover Flow, rotate the iPod upright again.
So what, exactly, is Cover Flow for? You could argue that it's a unique way to browse your collection, to seek ...