Don't re-invent the wheel. Here are some places where you can find scripts and libraries and other code snippets:
PHP Scripts
- PHPThumb - resizes images on the fly using GD Library and ImageMagick if available
- TimThumb or on Google Code - a trimmed down simpler adaptation of PHPThumb
- Simple PHP script to password protect PHP pages
- CaptchaCreator.com - PHP script to create Captcha's
- MagpieRSS - PHP script to parse RSS feeds. Use if ((strpos($rss, "http://") === 0) || (strpos($rss, "https://") === 0)){ condition to ensure that only http file gets passed to parser.
Client Side Script Libraries
- JQuery.com -- Javascript library
- Script.aculo.us -- web 2.0 Javascript
- DynamicDrive.com - DHTML scripts
- YUI -- Yahoo User Interface library
- Prototype Javascript Framework
- Dojo - Javascript toolkit
- Dijit
- Google Web Toolkit
- ExtJs.com
Other Libraries
- RegexLib.com - Regular expressions library
Useful Scripts
- Coda-Slider -multiple panels that you can navigate via tab or left/right arrows
- Uploadify - jQuery plugin for file upload feature