Rui CarmoXMind is a Java-based mind map editor that has a few interesting features (such as Gantt charts) and a nice (if somewhat infuriatingly “social”) map sharing site associated with it.
A serious initial drawback was that it compounded the fact that it ran (or rather, crawled) under Java with an Eclipse-like look (which I hate), but that has been solved in recent releases.
Also, it can import FreeMind files and now runs well on the Mac, Windows and iOS, so it has become my default.