Tutorialspoint Library
Gives great examples, including a test area for PHP, Bootstrap, JavaScript, AJAX, jQuery, CSS, HTML, and MySQL.
phppot
Blog has given great examples, especially around sample code (e.g. DB connections) and jQuery/AJAX.
Utilities/Spacing Notation
Bootstrap shorthand for margin spacing. Here are some thoughts on labeling utility classes.
Formatting Text
Some good insight on formatting a page with a variety of fonts... and other good links
Code with Chris
Blog talking about how to write an iPhone App