It’s a robust, free & open source (source available soon - licensed under the Eclipse Public License v1.0). After testing for a while, I put the radrails and RDT ( ruby development tools ) pluguins into Aptana. The result is a perfect web2.0 IDE to work on rails. Aptana IDE is supposed to be as good as dreamweaver. Aptana is a robust, JavaScript-focused IDE for building dynamic web applications. Highlights include the following features:

• Code Assist on JavaScript, HTML, and CSS languages, including your own JavaScript functions
• Ajax framework integration like DOJO, scriptaculos, AFLAX
• Outliner that gives a snapshot view of your JavaScript, HTML, and CSS code structure
• Error and warning notification for your code
• Support for Aptana UI customization and extensions
• Cross-platform support (mac, linux, win)