What is the iPod touch's screen sensitive to? I know that tapping on the screen with an object doesn't cause any reaction in the user interface (e.g. it doesn't cause a click of a button shown from an application). To what is the iPod's screen sensitive, and what can I use to replace my fingers?

The problem I am trying to resolve is that, using my finger to play a game, I don't see part of the screen, and my finger hits something that causes the game to end (you know, those little bombs that are launched in the play field when you are trying to slice fruits).
Sausages work very well! (not kidding)