This directory has just a few of the nifty php things I have learned.
I will try to get more up here but as I review I get sidetracked and forget...

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For a great reference go to: http://php.net/
 
Function Reference: http://php.net/quickref.php

Language Refence: http://www.php.net/manual/en/langref.php

And they have the whole thing available for a local install:
http://www.php.net/download-docs.php
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I put the entire language reference into a single text file which is nice
to use because it is easy to search the entire thing for references to 
things like "===" or "foreach" etc.

 php.net-language_tut   353 k