Also, what are other good concepts to learn in order to apply what I'm learning in more practical, useful, ways?
Sticky return key
I think it would be a bit easier to answer if you had a specific idea in regards to speaking to the OS. Such as how to write a graphical interface to report network traffic, cpu, and memory usage. And which language would be best to do that. Then we get to the above question how do I call the information from the OS so I can report it. I think an example like this in python would be learning about classes.
http://www.raspians.com - always looking for content feel free to ask to have it posted. Or sign up and message me to become a contributor to the site. Raspians is not affiliated with the Raspberry Pi Foundation. (RPi's + You = Raspians)