There's another site tossing their hat into the "best practices in PHP" ring (the other being PHP The Right Way) with what they call a "short, practical list for common and confusing tasks" in PHP - PHPBestPractices.org.

[Outdated tutorials and information is] one of the reasons why new PHP programmers are so frequently blamed for ugly, outdated, or insecure code. They can't help it if the first Google result was a four year old article teaching a five year old method! This document tries to address that. It's an attempt to compile a set of basic instructions for what can be considered best practices for common and confusing issues and tasks in PHP. If a low-level task has multiple and confusing approaches in PHP, it belongs here.

The site has sections for topics like:

• PHP & MySQL
• Single vs Double Quotes
• PHP regular expressions
• Validating emails
• Checking null and false values

If you're interested in helping out and adding more content to the site, contain the maintainer and let him know.