How I ride in traffic is sometimes based on auditory cues that I hear. For example, big engine or a truck/bus coming up, I'll move closer to the right as well as look over my shoulders to see what is coming. When it's a howling engine pushing high RPM's, I will pull over and check what it is coming up behind me. Once in awhile, you'll also get the, "On your left" to indicate another rider wanting to pass. Whatever it is, from brake squeal to engine noise, I find it useful to hear my surroundings.

I thought about using an iPod during my rides but never bothered. I do use my iPods when I jog but that's either on a track or a treadmill.