As I wrote in Better one file in the cloud than ten on the hard drive, when you mostly work on free software projects, then main frustration with a change of computer or a crashed harddrive is not lost files, but having to rebuild your development environment. The browser-based software development tool Cloud9IDE aims to solve that by moving the whole development environment to the "cloud".

With Cloud9IDE you get an excellent code editor thanks to the ACE project (formerly known as Mozilla Bespin), git integration and possibility to run your Node.js code right on the server. The editor supports multiple programming languages including PHP, Python and Ruby, but obviously JavaScript is the main target with very nice debugging tools. Cloud9IDE can either be used on the cloud, or you can run your own installation of the GPLd system.

What is good:

• Tight GitHub integration. All your GitHub projects are there, and you can register and log in using your GitHub credentials
• Fast and nice UI, at least on modern browsers like Chromium. It is probably also very fast on Firefox 4
• Integrated console and debugging tools
• No need to install anything, but still the possibility to run your own instance if you want
• Cloud9IDE is free software

What still needs love:

• In the current hosted version there is no way to commit stuff back to Git, or to work with branches
• No way to work with other Git repositories than GitHub
• Running code in Node.js doesn't seem to support any installable modules
• Some parts of the UI had glitches, like menus becoming transparent on hover