This Digital Voltage Meter for iPhone from ThinkGeek doesn’t reduce the number of gadgets you carry, so it doesn’t lighten your load. It does add to your feature set, though, because the free app from the iTunes store lets you capture data in a variety of ways and display it, email or post it to the web. The meter connects wirelessly to your iPhone, and the app makes your iPhone look like a multimeter, so there’s no learning curve to use the app. Features include: user definable data acquisition rate up to 20 Hz, user-definable audible measurement reading intervals up to once per two seconds, auto ranging and hold functions are built in, and fully-customizable on-device graphing functions (like graph scales and colors). The meter has a battery that’s rechargeable more than 300 times. It works with iPhone, iPod touch, and iPad with the free app that’s available in the iTunes app store. The Digital Voltage Meter is $219.99 at ThinkGeek.