I'd like to learn more about the radicals and primitives that make up 漢字. I'd like to know their meanings, and what the difference is between them. What resources are out there, particularly free resources?

I think this is pretty good: http://japanese.about.com/library/weekly/aa070101a.htm

When I was browsing the downloadable decks in anki, I saw one for radicals. I haven't looked at it though.

[Katsuo]

I once made a table comparing the traditional 214 radicals with Heisig's primitives.