One of the barriers to adopting a new tool, especially for a traditionally pen-and-paper activity like brainstorming, is the new tool's learning curve. Think over comes that with dead simple mind-map creating and easy exporting.
Think keeps things simple via an uncluttered and easy to use interface. You can do only eight basic things from within Think: open and close mind maps, save mind maps, export as images, and drag, create, connect and destroy nodes. You'll spend more time brainstorming and mapping out your ideas and less time fiddling with fonts, colours and other minor settings — you can't debate the best node colour when the only colour available is basic black.
Think is free to use but requires basic registration for saving nodes between user sessions. If you want to try out some more mind mapping tools, perhaps with a few more bells and whistles, makes sure to check out our previous Hive Five on the topic Five Best Mind Mapping Applications. Have a mind mapping tip or trick? Let's hear about it in the comments.