Might as well throw a buck in the toilet.

Cool idea, but i can guess a distance and get a more accurate measurement. Ever after spending way too much time screwing around with the settings,and holding the the phone just like they say, the readings were all over the place. In the time it takes to get a somewhat close reading, you could run to the store and buy a tape. A novelty at best. I have a 3Gs.

creep138 about Sonar Ruler