I have been working on one of the most requested Zest features, custom figures, and by EclipesCon it will be finished. Now you are no longer stuck with those little blue rounded rectangles. You can construct all sorts of custom figures, or even make use of an ImageFigure.
You can either do this by creating a CGraphNode, or in the viewer by using an IFigureProvider (as your label provider). Now we can construct some UML Style visualizations using Zest. Is anybody interested in trying to hook up an SVG parser (I think batik is part of Orbit)?
Want to learn about this and other cool Zest tips and tricks. Come see my talk at EclipseCon.