What materials did you end up using to successfully emulate the human touch anyway? What was the trick to getting these devices (esp. iPhone) to register the "touch" as a viable touch? Tell us all your secrets! ;)

I believe the reason the Motorola Droid did so terribly is solely due to the application used to test it. I have that application and it is absolutely terrible for trying to draw. I have another application called Draw(er) and it works perfectly. The tracking is very good and i can draw very straight lines with it.