JSGB is a Nintendo GameBoy emulator. Written in JavaScript and HTML5. Integrates a debugger with breakpoints support, memory, viewer and more... You can test it here: www.codebase.es/jsgb/?v=0.02
The Open Log Engine is a powerful tool for advanced logging in games or programs. It easily allows you to make logging outputs in your program and analyse them afterwards with the Open Log Viewer, which provides you a powerful filtering system.