When starting a new project, it is usually a very good idea to re-use code. This can be your own snippets or a library/framework. They save so much time. And, working with stable code makes sense.
Eden is an open source and free PHP library for developing fast. It includes lots of components for auto-loading, event driven, file systems, caching, templating, i18n, databases, web services, payment gateways, shipping and cloud technologies.
To give a better opinion, it has ready-to-use functions for working with Google services (Youtube, Drive, Contacts, Analytics, Checkout, Maps), Facebok, Twitter, Tumblr, PayPal, Authorize.net, FedEx, UPS, Amazon + Rackspace Clouds and much more.
And, not even counting standard features like database, e-mail, templating, etc.
If you are using any CMS or PHP frameworks, that is ok too as Eden plays well with others like Wordpress, Drupal, Joomla, Magento, Symfony, Zend Framework, Code Igniter, Laravel and even Titanium.