http://www.wired.com/design/2013/12/with-location-ifttt-links-apps-to-your-real-world-activity/
Pretty cool use of a rules based business logic. See lots of potential for this from a security perspective.
http://www.wired.com/design/2013/12/with-location-ifttt-links-apps-to-your-real-world-activity/