This seemed to me like the easiest thing to find, a simple way to display my classes as UML in eclipse
But except this: http://java2uml.gforge.enseeiht.fr/ and this http://sourceforge.jp/projects/amateras/releases/ I haven't found any new, maintained and "good" implementation (with all due respect to the above two)
Anything else I've missed?
Did you consider
Creating UML 2 diagrams with Eclipse UML2 Tools - Tutorial ?
I had older references for such tools, but the new ones are build upon UML2 project (described in the tutorial). MDT-UML2Tools is in the making, Omondo is there, but not free.
Papyrus UML, for instance, is based on UML2 Tool.
The full list is available at Eclipse marketplace.
I generally use Doxygen to create documentation because it has built-in support to generate inheritance diagrams. There is an Eclipse plug-in for Doxygen called eclox. It is not longer maintained since December 1st.
Doxygen is based on Graphviz. You could directly use LightUML, which is based on Graphviz to create UML diagrams in Eclipse.
Annotate your classes with Ecore's annotations, then you can import an Ecore file from them. You can initialize an Ecore diagram from them, or export it to UML, and initialize a class diagram from it.
See http://www.reversejava.com for a dynamic reverse engineering application which generates UML Sequence diagram and view of Participating Class diagram from any Java Application at runtime All you have to do is just run your application and sit back. Reverse Java runs in background tracing all the activities happening inside your application and creates UML diagram for you.
You also have options for, excluding packages,editing the Sequence diagram and exporting the diagrams as PDF or Image.
And its not expensive !