I am now a supporter of the crowd-funded open-source project known as codebender. Codebender is a cloud-based Arduino IDE that provides the capability to edit, compile and upload your code to an Arduino from a web browser.
The cloud based IDE implements clang which is a compiler that provides descriptive warnings, fast compile times, low memory usage and compatibility with GCC. In addition, codebender contains built-in highlighting, Arduino documentation, support for libraries and a serial monitor.
Pledge $150 and you will receive exclusive access while the project is still in development, a monthly newsletter and an Arduino Ethernet preloaded with codebender’s (upcoming) TFTP bootloader. The bootloader will allow any Internet connected Arduino to be programmed through a web browser locally or away from home.
All of the sources for codebender can be found on the associated Github page.