Octohunt - Search to find developers in your city on Github.
Sourcegraph for GitHub - Browse and search GitHub like an IDE
CodeFlower - CodeFlower visualizes source code repositories using an interactive tree.
JSONView - Validate and view JSON documents.
GitHub Visualizer - Enter user/repo and see the project visually
JSON Viewer - The most beautiful and customizable JSON/JSONP highlighter that your eyes have ever seen.