CaliperTool for iPhone and iPod Touch
Since I bought a lathe and have started doing some metalwork I have found myself spending a lot of time measuring a piece and then trying to convert the measurement from thousandths of an inch to fractional inches - usually to find a drill bit.
I wrote CaliperTool to help.
Enter a measurement value in inches or millimeters and CaliperTool will find the closest 1/64" values above and below your measurement and print them along with their respective errors.
It will do the same thing with standard "letter" and "number" drill bits, listing the closest above and below your measurement along with errors.
It will also do a simple metric conversion and list the measurement in millimeters or inches, depending on which unit you entered.
You can buy CaliperTool either from iTunes or by visiting the App Store on your device. In either case, searching for "CaliperTool" will get you to it. Or, you can use this link
to start up iTunes on your computer and go straight to it.