Recently it was revealed that the NSA is working with US technology companies to gain access to users' private information. This webapp visualises your social network from your Gmail and social network accounts. It gives you an idea what can be revealed about you from scanning your private metadata. One can imagine the NSA or GCHQ using similar tools on their targets.
The darker the line and circle the more important this person is to you. The larger the circle the more connected this person is.