Code

PHP

Pancake Payments - A really simple invoice generator with client management that helps you bill clients and send payment requests. It's built with CodeIgniter and it's themeable (even for the backend).

PyroCMS - A simple yet powerful CMS built with CodeIgniter. Designers, developers and end-users all interact with it in the way the expect to, instead of trying to make ONE INTERFACE TO RULE THEM ALL, which always blows - without exception.

PHP The Right Way - There’s a lot of outdated information on the Web that leads new PHP users astray, propagating bad practices and bad code. This must stop. PHP: The Right Way is an easy-to-read, quick reference for PHP best practices, accepted coding standards, and links to authoritative tutorials around the Web. .

CodeIgniter Libraries

Cache - a partial caching library for CodeIgniter. It allows you to write and get chunks of data to and from the filesystem manually, or cache specific model and library calls.

Curl - Interact with other web-pages, API's and servers over HTTP, FTP, via proxies and through HTTP authentication, all with very simple syntax.

CLI - Work with CodeIgniter over the command line and have access to a few useful methods like read, write, wait, new line, beep, etc. 

Dwoo - Use the Dwoo templating system with CodeIgniter in a very tidy way, very similar to Smarty but less bloated.

Prowl - Send iPhone notificiations from your CodeIgniter application via the Prowl service.

Rest Client - Interact with RESTful API's in your CodeIgniter app using a very simple syntax.

Rest Server - A fully RESTful server implementation for CodeIgniter using one library, one config file and one controller.

Template - Construct complex page templates using layouts, partial views with support for modules and themes, meta-data, breadcrumbs and automatic/manual page titles.

Unzip - Extract ZIP files in CodeIgniter without installing any PECL extensions for PHP.

ExpressionEngine 2

Rest - Integrate RESTful API's into your ExpressionEngine 2.0 website with this Rest module. You can list Tweets, search for Digg articles, show off Flickr photographs and interact with any open RESTful API.

Widgets - An ExpressionEngine 2.1 module that allows even your least experienced client or to manage chunks of intelligent content on their site without needing to learn loads of tags, HTML or call you in to help.

Miscellaneous

DBAD License - As developers we all want to protect our code from people that try to steal, sell, infringe or just generally rip us off and sometimes we don't really care. This license meets in the middle to just stop people from being a dick.

ilikemywomenlikeilikemy.com - Enough said.