We-e-e-ell, I'll try not to get started too much on the whole iPod/no iPod thing - but if you're having difficulty without it on race day, it could be because you're not paying attention to your body when you're listening to the music. Running with a metronome really focuses your attention on the turnover of your legs. Then you build muscle memory and it becomes easier, not harder, to maintain your cadence when you don't have the metronome.
Oakleaf: May have found a good use for an i-pod for you! I-Tunes has an entire "album" of a downloadable metronome. It's called "Simple Clicks". Each track is a different pace. No music, just click click click! I admit it, I paid for it (only $9.99 compared to having to get off the couch and go to the music store and probably pay more). I'll let you all know how it goes!

Oh... and the "not paying attention" is probably why I listen to music... can't listen to my breathing and the pounding of my feet and heart, the gasping for air...