Xylophon is a plattform independent UML modeling tool written in Java.
It supports the most of the diagram types in the UML 1.5 standard.
I try to keep Xylophon as little as possible without lost of any feature making it a good UML tool.
It is/will be a group of useful functionalities like:

• Full UML 2.0 Support
• Repository and Release Management
• Round-Trip Engineering
• HTML Documentation
• Pick Lists for Classes and Methods
• Data Modeling Integration
• Printing Support
• Integrated Source Code Editor
• Scripting tool for customized documentation, customized code, reports, and metrics