Bibliography on the Unified Modeling Language
contains references to publications about the UML.
UML Resource Page
contains technology submissions, articles, and links.
UML Tutorial
covering all aspects of modelling with UML.
UMLet
web-based tool for creating UML class diagrams.
Unified Modeling Language Dictionary
Unified Modeling Language FAQs
Unified Modeling Language Resource Center
contains documentation, quick reference, and whitepapers.
What is the Unified Modeling Language?
by Sinan Si Alhir. Discusses the history and utility of the UML.