I use Mind map on a day to day basis when I need to structure a topic, especially in brainstorming phase.
For this, I use freemind which an open source dekstop application.
I've discovered last week a gadget for Google wave that allow you to build a mind map within a wave.
Very powerful to work remotely.
Of course this first version has limited functionalities, but it's ok to start to use it.
All the informations are on "Bruce's blog"