If your site is one of the 12 million domains using the PHP scripting language, then PHP.net is a good place to find PHP related information. Links to resource sites, tutorials, manuals, books and much more.
ScriptWiz.com Offers hundreds of free and commercial scripts to improve your website. The site also offers tutorials as well as a breakdown of scripts by date, most popular and top ranked.
ScriptsFinder.com Offers hundreds of free and commercial scripts to improve your website.
The Perl Archive A good site to visit if you're looking for CGI scripts. With over 3,953 scripts in 169 categories, there's something for everyone. The site also has a learning center and discussion forums if you need CGI tips or help.