The OpenWeatherMap C SDK by Pebble Hacks allows developers to integrate the OpenWeatherMap API into their C applications. This SDK can be used to get weather descriptions, short descriptions, temperatures (in K, C, or F), and location names.
Geolocating your users can create a better experience, but it can also be used in devious ways. For example, cathysteeth.com claims to have a cosmetic dentistry solution discovered by a mom. And wouldn't you know it, Cathy lives in your home town. And your home town.
Have you noticed the many tools to share your location? There's FourSquare and Gowalla, both about a year old. Then there are old-timers like Brightkite. And now, there's one that works with all three (and a couple more).