I downloaded FreeMind per a comment posted on HN a few days ago, and so, am liking it. Its pretty comprehensive, and although I have only used it for minimal mind-maps, the fact that there are keyboard shortcuts for most of the important functionality definitely makes it very useful.<p>And its Java, so I can run it across my Windows and mac boxes.
Interesting implementation, I do like how they've kept the node graph simple. They've made the classic error of forcing you to register before you can play with the application. It's also little cumbersome to add nodes. A better interface might be to double click on the parent node to create a sub-node or something of that nature.