Craig - + a bunch for the suggestion and idea. It would be fantastic to have some tutorial coverage on mastering and with Sonar tools for that.
I like just about all of the suggestions above. Great crowd sourcing on thinking about what could be helpful.
I would think the tutorial could be cool if you covered mastering a few tracks - each with its own set of problems, and how you would point out what's making each one sound bad, and how to approach deducing how to get each one better.
I would add that it would be cool if you discussed reference tracks. I realize you'll be using Sonar stuff only, but I'm using Magic A B now at the very end of my bus/signal flow and that's really convenient for flipping back and forth between what I'm working on and a song or songs of a similar energy.