Back in 2001 when I first got started with Ruby, there were no IDEs for Ruby, so I decided that writing one would be a good way to learn Ruby. A few months later I joined forces with Rich Kilmer and we developed FreeRIDE–the only Ruby IDE that is written in Ruby. But these days its a much different story as there is a veritable plethora of Ruby IDEs available as vendors almost fall over themselves to provide Ruby support.
Someone (if anyone knows who it is that wrote this blog entry, please post a comment) has published a very nice comparative review of three of the most popular IDE choices: IntelliJ IDEA, Sun’s NetBeans, and the Eclipse based RadRails/RDT. Here is his main feature comparison chart, go read the whole review for his qualitative assessment of these three IDEs.