Visual Studio UML plugin: UML diagrams, use case modeling, textual analysis.
Editor: SDE for Visual Studio is a UML CASE tool/plug-in tightly integrated with Visual Studio. This UML modeling software supports full software lifecycle - analysis, design, implementation, testing and deployment. This UML CASE tool helps you build quality applications FASTER, better and cheaper. You can draw all types of UML Diagrams in Visual Studio, reverse engineer C# code to class diagrams, generate C# code and generate documentation.

SDE-VS Features:
+Support UML version 2.1
+Business Workflow diagram
+ (New Feature)
+Handi-Selection (New Feature)
+Command-line operations (New Feature)
+User Interface Designer (Enhanced)
+Data flow diagram
+Use Case Details Editor - An all-in-one environment for specifying a use cases details including general model specification and use case descriptions
+EJB Diagram - Visualize EJB systems
+EJB Code Generation
+ORM support - generate Java objects from database
+Database generation - ERD to database tables
+Database reverse - existing DBMS to ERD
+Reverse engineering - code to model, code to diagram
+Reverse engineering Java, C++, XML Schema, XML, .NET exe/dll, CORBA IDL, XML Schema and Python (Enhanced)
+Code Generation - model to code, diagram to code
+Java Round-trip engineering
+Automatic synchronization Between source code and diagrams
+Automatic diagram layout
+Modeling collaboratively with VP Teamwork Server, CVS and Subversion (Enhanced)
+Shape editor
+Import Rational Rose project, XMI/export XMI, Telelogic Rhapsody Project (New Feature)
+Support Stored Procedure and Database Trigger (New Feature)
+Export diagrams to JPG, PNG, SVG, EMF, PDF
+PDF/HTML/MS Word Report generator
+Multilingual support
+More...

Other UML Modeling Tools / UML Plugins:
Java Platform (Windows/Linux/Mac OS X):
+SDE for Eclipse
+SDE for Oracle JDeveloper
+SDE for Borland JBuilder
+SDE for IntelliJ IDEA
+SDE for NetBeans
+SDE for Sun ONE
+SDE for WebLogic Workshop
+More SDE... you can free download SDE for Visual Studio (PE) for Windows 5.2 now.