I've developed an electronic ballpoint stylus for the iPad. The tip is a very smooth solid metal sphere of 3 mm diameter. It glides easily over the glass surface of the touchscreen. The small size of the tip makes it attractive for drawing or handwriting, as one can see the point of contact of the stylus with the screen. The large blunt tips of the styluses on the market hide the work being done.
If you'd like to see my stylus in action, search YouTube for "JCMiPadStylus".