Researchers are investigating methods to give audio feedback while you navigate your scroll wheel. I know plenty of Apple savants who have the structure memorized, but for those of us somewhat new and reluctant to the iPod experience, this could be a great way to get around your music player.
Until they do introduce this, just remember: driving downhill on the Grapevine (en route to L.A.), while clicking through your iPod and trying to decide whether to play Ghostface or El-P, is a very good way to get you a speeding ticket. And when you don't pull over right away because you didn't notice the lights on account of browsing your iPod, that's a good way to really piss of the 5-0.
Someone in the comments field also notes that Rockbox, the alternative firmware for people brave enough to risk killing their iPods, already has a feature like this.
Technology Review article