We've seen all kinds of touchscreen solutions for when fingers don't suit. A mobile-centered blog suggests an anti-static bag can also make the touch-sensitive grade.
PocketNow.com demonstrates how a rolled-up anti-static bag, the kind that hardware geeks often accumulate over time, can fit the bill on a Zune HD, and presumably other phones, as well. I gave it a go using a small bag from a MintyBoost kit and a Nexus One, but didn't have much luck—then again, it didn't look like the kind of full-fledged static bag I remember from my PCI card memories.
You'd probably want to arrange your anti-static material such that a hard edge wasn't swiping and scratching your screen, but it's a good starting point for making your own convenient stylus that also makes for a neat talking point.
How To Make A Free Capacitive Stylus [PocketNow.com]