This small app is actually part of the larger project, Friendly Island, but has been extracted and made to standalone because I like it so much. It makes use of jQuery and D3.js for its functionality, and Bootstrap for the interface.
Users can enter the names of some friends, and then go through that group of names and connect those people who know each other. If you mistakingly add a connection, simply click the errant leaf to remove it. When everyone has been linked, users are presented with a D3 force layout of their network. This standalone version also displays the JSON output of a user’s network, so it can be copied and saved.
See some screenshots below or play around with the example.