This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
They have a competition about once a week and you can try out all the past competitions. I'm hoping to get back into it again myself. It's set up pretty well - they have system tests you can run to test your code so it makes for a great learning experience.