I saw this for Android http://forums.watchuseek.com/f11/rel...es-822115.html
and I have seen a similar app which runs on Apple phones.
It uses the microphone to listen for the ticking of a watch or mechanical clock and compares it to its own more accurate internal clock. By accurately timing the ticks it can tell if there is variation between positions and if the watch is running fast or slow even with a sample as short as a few seconds.
I imagine it would only take a few dozen lines of code to create such an app with graphing but I dont have the space on my netbook to install scratchbox. One issue is getting accurate time without background processes bogging the measurement of time or sound inputs.
It would be a cool app for watch regulating/repair geeks or before buying a used mechanical watch.