You may have heard that in late October 2006 the UK's Open University, which specialises in adult education including by distance learning, followed in the footsteps of MIT's OpenCourseWare by releasing some of their course material free to the public on the Web via their OpenLearn site (with an associated site LabSpace).
As with the MIT offering you don't get a degree, but you can access their material for free. So far, their IT and computing courses seem either too basic or too advanced for me, but there are materials on loads of other subjects from art, history, business and health to maths/statistics, languages, science/nature, society and technology, as well as study skills.
One interesting thing though is that, even if you don't download their course material, you can download their free mind mapping software ("software tool for visual thinking") called Compendium, which they're generously providing not only for Windows but also for Mac OS X and Linux (you do need to have Java installed on your computer, which you can get for free again). There are screencast tutorials too.
I've installed it but haven't played much with it yet. It seems to have a decent number of keyboard shortcuts, one of my main personal requirements, at least - yay! More if/when I've tinkered further with it. But it's free, so do give it a go if you're looking for "knowledge mapping", "concept mapping" or mind mapping tools. (There's also other free open source software for mindmapping available, e.g. Freemind, also for Windows, Mac OS X and Linux - I've downloaded it myself but again not had a chance to compare them yet).