If you don't want to go the full hog and shell out for an expensive, commercial mind-mapping tool like MindVision Mindmanager, Freemind or ConceptDraw Mindmap, then there's an online solution called MindMeister that might just suit your needs.
First, the basic version is free and that allows you to create up to six mind-maps that you can share with others or even collaborate on with them. You can also import maps from Freemind and Mindjet MindManager, Export maps as RTF or images and publish your maps online.
It even comes with downloadable tools to let you edit your maps from the Mac OS X Dashboard or Windows Vista Sidebar and there are browser extensions for Firefox and Internet Explorer that let you add web content to your default map as you browse.
Stepping up to the paid version lets you create unlimited maps, export them as Freemind or Mindjet MindManager, embed your maps in blogs or websites and it comes with full SSL encryption.