Visual Paradigm for UML (VP-UML) is an easy-to-use UML CASE tool that supports full software development life-cycle - analysis, design, construction and deployment. This UML tool helps you build quality applications faster, better and cheaper. You can draw UML diagrams, generate code from diagrams and vice versa, and generate documentation in different formats. This UML modeling tool also provides plenty UML resources including UML tutorials, demos and sample projects.

VP-UML Features:
+Full UML notation support (use case diagram, sequence diagram, collaboration diagram, class diagram, object diagram, package diagram, state diagram, activity diagram, component diagram, deployment diagram)
+Textual analysis for identifying candidate use cases, flow of events, classes...
+CRC diagram
+Use case modelling (use case description, scheduling...)
+OOAD support - object-oriented analysis (OOA), object-oriented design (OOD)
+Round-trip engineering support
+Code Generation - generate code, model to code, diagram to code (UML to code, UML model to Java)
+Reverse engineering - code to models, code to diagram (Java to UML models, Java to UML diagram)
+Reverse engineering Java, C++, XML, XML Schema, Dot NET dll/exe, CORBA IDL
+Real-time synchronization between source code and class diagrams
+UML Report generator for generating HTML/PDF document
+Automatic diagram layout - rearrange classes and connectors in UML diagrams in different styles
+Import/export XMI file
+Import Rational Rose project
+MS Visio Integration - drawing UML diagrams with stencils from MS Visio
+Export diagrams to SVG, PNG, JPG...
+Plugin and template
+Multilingual support
+More...

Other UML Tools / UML Plugins:
Windows Platform:
+SDE for MS Visual Studio .NET
Java Platform (Linux/Windows/Mac OS X):
+SDE for Oracle JDeveloper
+SDE for IBM WebSphere (WSAD)
+SDE for Borland JBuilder
+SDE for IntelliJ IDEA
+SDE for Eclipse
+SDE for NetBeans
+SDE for Sun ONE
+More SDE...