Over the past couple of years, the buzz has been growing steadily around a new generation of services designed to allow you to share your offline location with members of your online social network. The core concept isn't new, but new players have given it a spin that's winning fans, fast. Social media mavens see these services as evolutionary vehicles for extending the social web into the real world. But underneath the high-concept talk is simply a very cool social networking capability that you might want to try. Here's what all the fuss is about.