It never ceases to amaze me what you can do with an iPhone, especially when paired with add-on accessories. Case in point, Vaavud makes a Smartphone Wind Meter ($40) that attaches to an iPhone, iPad, or Android phone. Unlike most accessories that connect via Bluetooth or Lightning, this gadget connects via the audio-in jack, just like the Square credit card reader. Because newer iPhones have the audio jack on the bottom, you flip the phone upside down and run their companion app while holding the iPhone in the air.
This replaces dedicated devices like you might see in the movie Twister. In fact, the other day, Twister was on TV and I grabbed a screenshot of just such a gadget. Even if you're not a hardcore tornado chaser, you might want to measure wind speed at a sporting event.
We are getting closer and closer to Mr. Spock's Tricorder. The iPhone has numerous sensors built-in, but with clever add-ons from folks like Vaavud, there's no limit to what an iPhone can measure.
