What order should we take PHP classes within the library that are not part of the PHP Development track?

Austin,

Chris is spot on. The courses that aren't part of the track aren't meant to teach you the fundamentals of PHP, they are just addons that'll help you broaden your scope. The courses can be taken in any order you want and I advise you to do the ones that interest you the most first. The tracks are meant to teach you the language while the addons take you to different areas once you learn that language. Think of it as showing you how to code and the addons help you take what you've learned and apply it or simply how to use it.

As far as your second question goes: Team Treehouse is always looking for new material that peaks the interest of their students. However, since there's a whole range o topics out there, knowing what to add as a course can be troublesome. They want to add courses that they know their students want. Have an idea on what they should do next? Let them know by posting your ideas on these forums or contact them directly with your input. With enough requests on a subject I'm sure they can fit it in. Of course the next thing would be to find the appropriate teacher that knows the subject content in order to teach the course. Not all teachers will know every single subject and finding the right one might take time. But keep on voicing your requests. Without them, Team Treehouse wouldn't know there's a demand for it. Congrats on completing your PHP track and keep on learning!

Cheers!