Packagist is the main Composer repository. It aggregates public PHP packages installable with Composer.
Yet another syntax highlighter for PHP
Asynchronous XMPP Library for PHP
Event based socket library for php, supports (a)synchronous clients and servers.
Some utilities like Events, Properties, Timer for PHP (especially CLI)
PHP Xml Serializer, with annotation support.
Asynchronous, Non-Blocking, Event Driven Xmpp Library, which utilizes php 5.4 features.