I would like to suggest my own PHP2XMI / PHP2UML tool with web interface for the "UML Software" category:
http://www.gammelsaeter.com/php2xmi/
It parses PHP classes and generates interfaces, classes, inheritance, implementation etc as an XMI file. The XMI output has been tested with argoUML, StarUML and Umbrello, and works perfectly.
I am very interested in feedback and suggestions to improve. I can mention that I have plans to extend it with Umbrello support in the XMI output so that the classes already is set up and the user do not have to put every class and interface in the right place.