This site is the Ibuildings developer portal site. I've written for it since its launch (the contributors are mostly Ibuildings employees), in fact its very first article was mine. Since then I have become its Editor-in-Chief and edit the tutorials more often than write them. The site is a great source of good quality content however!

Getting Started with Memcached
New Memcached Extension for PHP
Using PHP Code Sniffer
Web Services for PHP Developers