Finger fatness on a pad or pod or phone doesn't matter much. Even a stylus isn't particularly advantageous. The screen (OS) figures out the perimeter of your finger, and averages it to a center. The software then applies a brush diameter to that center point. I think sketchbook even lets you offset the brush from your finger, so you can see more precisely.
There are a couple of styli that have a plastic window with a crosshair that are a little better for visibility and accuracy, but they're too fussy for me to use. I have a bamboo stylus, and it's OK. All of them lack something in response vs your finger. It isn't anything compared to using a graphics tablet.
they're great! (my effort is pretty poo compared to those links) Thanks for sharing!
yeah dm, its not really a substitute for my cintique - but its thin,light and portable... so probably good for sketching - and I've already got ipadfingeritis after only a few days...