What is Mac OS X? has to be the best technical article describing the lower level aspects of MacOS X I have read in recent times. Next to developer documentation, its a good read for MacOS X experts. The content and style reminds me of a 2.5 days course I created and ran 10 years ago: “Mac Support Expert”
Mars nerds: you can use the same software the scientists are using to visualize the data from the Spirit rover: Maestro. Installed and worked like a treat.