Graphviz in Eclipse
It is for things like this that I like Eclipse so much: I just love Graphviz, which has an awesome UI in its Mac OS implementation, but isn’t maintained and uses an old version of DOT. When I saw the Windows version I was totally disappointed. Since I did some Graphviz-rendering in Eclipse before, I decided to pick up Wayne Beaton’s Image Viewer from the Eclipse Evangelism site and make it a Graphviz viewer. Now I have a multi-platform, open-source and up-to-date implementation that is on par (at least for the way I use it) with the best existing platform-specific solution, and it even has my favourite editor and versioning, etc. included (download it for Eclipse 3.2 or for Eclipse 3.3). The Plugin adds a Graphviz View that will display a DOT file, listens to changes in DOT files in the workspace and exports as PNG and PDF.
On the Mac, you should use the latest, non-UI version of Graphviz, as it supports both the great Mac OS features as anti-aliasing of the edges in graphs (by using Quartz or something) as well as support for the latest DOT commands, such as ports for edges (which can be used e.g. for UML activity diagrams, like this).