Hmm.. I don't know if this is the right place to suggest an app (My apologies if it isn't the right place,) but here it is: have the iphone/ipod touch act as a graphics tablet. This existed for the Newton and for Palm OS (http://www.tow.com/software/writehere/) I guess the question is.. without a stylus is the screen good enough to be a tablet. My guess is yes given apps like No.2 (http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=285049917&mt=8). Anyways, I think that this would be an interesting, unique and useful app. Just my thoughts 
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