Sourceforge is a lot more than a script directory but I should not have missed it. Google has something similar as well.
This site is great: http://www.eioba.com/c125/php and this: http://www.eioba.com/g5/web_development (over 60 articles about programming in PHP, MySQL and AJAX)
I've been receiving a little traffic from http://www.atomicphp.com/ recently. They seem to be scraping data from other sites so if you've already posted your projects at the big sites (hotscripts, scripts etc) then just check they don't already have you before posting again.