The UML is owned by the Object Management Group (OMG) , which maintains a site that contains useful introductory information about the standard and how it is being updated for future implementation. The OMG also provides a list of lists of processes and tools
DOORS is a widely used and portable requirements management tool.
Rational Software : tools for system specification, modelling, version and test management, and code analysis.
Rhapsody is a high quality tool produced by Telelogic, which generates significant amounts of executable code from UML models.
The following links are to lists that provide information about a wider variety of products on the market supporting software engineering: