[CeiII]

MindNode (http://mindnode.com/) is not bad for Mac. I've also found FreeMind (http://freemind.sourceforge.net/wiki/index.php/Main_Page) pretty good in the past.

[ktizo]

I love freemind, mostly for how quick it is to use from just the keyboard, and also for the the platform independence which makes it very easy to use it collaboratively.