PHP: Hypertext Preprocessor - Server-side HTML embedded scripting language. It provides web developers with a full suite of tools for building dynamic websites: native APIs to Apache and other web servers; easy access to MySQL, Sybase, Oracle, and other databases; IMAP; LDAP; HTTP headers and cookies.
Hardened PHP - Adds security hardening features to the language. Include news, libraries, Hardening patch, services advisories, a forum and a system for advanced protection of installations..
PHP Club - A programmer's group united by a desire to develop PHP technologies in the Internet. News, articles, applications and FAQ..
PHP Everywhere - John Lim's weblog with comments and reviews. Links to his longer articles and manuals..
Quality Assurance Team - Volunteer coders dedicated to providing coders with quality assurance..
Making the Case for PHP at Yahoo! - Slides from a talk where Michael J. Radwin makes the case for using PHP over other languages. (October 25, 2005).