There are so far 3 free mind mapping application that i know is able to run on Mac.
Freemind - one of the famous open source mind mapping application that is free, it support multi platform include windows, linux and mac.
MindNode - a mind mapping application that only run on Mac , there are free edition [...]
If you know about mindmap and wish to mindmap every where ( as long as you are able to access to internet ) , there are 2 web based mindmap service appear recently.
MindMeister
Currently in private beta mode
Basic feature is included, font color and icon feature available
Line format should be improve example include different color, weight [...]
