Derek's Anti-Framework Framework (couldn't think of anything for "Y")
Disclaimer: I'd advice against using this library. Rather, just browse the code and grab concepts from it. I haven't done any coding on this since 2009, there is no documentation, few examples, it was built with only my needs in mind, and there is certainly room some performance tweaking.
After spending years working in various PHP frameworks (CodeIgniter, Kohana, Zend, etc...), I grew to dislike how they box you in to their way of doing things. So, I decided to write my own, basic, no frills framework.
It certainly doesn't provide you with a whole lot of functionality out of the box. All you get is:
- RESTful API
- A Twitter OAuth library for authentication
For a basic, low-traffic site, that's about all you need to get started. The rest you can, and should, code yourself. Whenever I start a new site, I usually begin with this library, and build from there.