Just an extremely simple naked PHP application, useful for small projects and quick prototypes. Some might call it a micro framework :)

A simple PHP model-view-controller framework, built step-by-step as part of the "Write PHP like a pro: build an MVC framework from scratch" course on Udemy.

A Most Simple PHP MVC Beginners Tutorial

StupidlySimple Framework for PHP - MVC Framework for lazy developers

Source files for Tuts+ tutorial: Building a Bootstrap Contact Form Using PHP and AJAX

A simple newsletter sign-up form using Ajax, PHP and MySQL

AjaxCRUD - Manage mySQL Database with PHP and a few lines of code!

PHP + AJAX скрипт отправки форм на E-mail

Simple PHP & jQuery AJAX Example

Simple To-Do List w/ PHP & AJAX

A simple Ajax App with PHP backend

PHP объектно-ориентированный подход. Учебный проект - 16 уроков.