1.
http://www.dynamicdrive.com/
Welcome to Dynamic Drive, the #1 place on the net to obtain free, original DHTML & Javascripts to enhance your web site!
2.
http://planetsourcecode.com/
The largest public source code database on the Internet with 12,812,533 lines of code, articles and tutorials in 11 languages,as well as 1,574 open job postings
3. PHP
http://www.opensourcescripts.com/dir/PHP/
http://php.resourceindex.com/
http://www.scriptsbank.com/
http://gscripts.net/
http://www.scripts.com/php-scripts/