An accelerometer-based ruler. Finally a useful "tape measure" is available for the iPod Touch and iPhone!
AccelaRuler 1.0 was an Apple Staff Favorite, and AccelaRuler 2.0 is even better!
#5 "iPhone Apps for the Home", Newsday
"There are certainly times when a quick-and-dirty estimate of the size of a flat surface is all you need, and AccelaRuler can deliver that", MacWorld
It's easier to see than to explain -- to...