Six Degrees of Wikipedia - Find the shortest path between two subjects
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Intch - Professional networking app
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
WikiBinge - Discover how all things are vaguely connected
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.