Don't forget the ever useful Tricorder app for Android.... guy named Moonblink wrote it. You'll have to scrounge for it though. CBS (in all its stupidity) issued a DMCA to Google Play forcing off their market.
It still seems to be lurking here:
http://www.freewarelovers.com/android/app/tricorder
But basically - what Fluff said, ditto line for line. I don't see how anyone uses these things for their "primary computing device" but as a utility belt tricorder they're pretty useful.