Here are some interesting specialty UML sites that might be worth visiting:
Define a term: If you need to look up a UML term, try Kendall Scott’s UML Dictionary at www.softdocwiz.com/UML.htm.
Ask a question: If you want an interactive Ivar (a chatterbox in the form of a virtual simulacrum of Ivar Jacobson) to query about UML, try Jaczone’s Cyber Ivar at www.jaczone.com/cyberivar.