The OpenAddresses R SDK by Scott Chamberlain is an R client for data from OpenAddresses. The library serves to make it easy to retrieve the data, as well as combine data sets and visualization. OpenAddresses is a web portal for the management of Open Source worldwide localized postal addresses.
Swellcast combines all weather data needed to forecast surf conditions for surfers around Australia, and consolidates the data into a user friendly interface that takes the complexity out of understanding when and where the next big wave will appear. Swellcast also offers the forecast data and surf conditions through the Swellcast API.
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.