Web development
PHP
w3schools - One of the best tutorial resources available for pretty much anything.
Tizag.com - A brilliant PHP tutorial site with emphasis on examples.
XmlWriter - A great PHP class for generating XML documents.
Browsershots - Renders screenshots of a given URL on multiple browsers.
Javascript & AJAX
Script.aculo.us - Some lovely JavaScript :)
Cyber Dummy - Shows off a bit of what AJAX can do.
Lightbox JS - A simple script used to overlay images on the current page. Based on prototype.
Fancy Form - Allows HTML form elements to be gracefully replaced.
Calendar - A calendar
Starbox - Rating system
Web Stats