If you've never used mind-mapping software, you're missing out on a great way to quickly organized your thoughts, brainstorming sessions, high level site-maps, etc. Mind mapping tools allow you to rapidly group ideas, created structured trees, and easily move ideas from one parent to another.

I've used MindJet Mind Manager for a few years now, and it's a truly great tool. It's 'lite' edition runs 100 bucks and the pro edition runs 350.

A friend of mine recently introduced me to an open source variant called FreeMind. It lacks some of the more advanced features and OS integration that Mindjet offers, but for 95% of my mind mapping uses, it works just fine.

It's a java app, and generally i don't like java apps as they often take longer to launch, but FreeMind fires up surprisingly fast.

here's a screenshot: