I was looking for a simple freeware for generating UMLs and class diagrams spesifclly.
Here is some of the better ones I have found:
open source UML modeling tool.
Another cool open source UML modeling tool.
A freeware by white magic software.
AmaterasUML is an Eclipse plug-in for drawing UML class-diagram, and UML sequence-diagram.
The ObjectAid UML Explorer is a UML plugin for Eclipse. It provides a graphical view on your Java source code.
UMLet is an open-source UML tool with a simple user interface
Of course NetBeans itself comes with a very good UML tool built in.