PSX is a framework for developing dynamic Web sites in PHP. The goal of PSX is to help you develop RESTful APIs serving Web standard formats like JSON, XML, Atom, and RSS. It has a focus on social technologies and provides classes to use and implement OAuth, OpenID, Opengraph, Opensocial, Opensearch, PubSubHubbub, Atom, and RSS.
Gaze is a lightweight Gmail checker that sits in the system tray and notifies you of new messages in your inbox. You can configure how often the program will use the ROME API to check the Atom RSS feed for your inbox, as well as optional combined notifications, custom browser actions, theming, and more.
Syndicate Press is a Wordpress plugin that lets you include RSS feeds directly in your Wordpress posts or pages. This plugin provides a very easy-to-use administration page and includes great features such as feed caching, filters, and multiple display options. The plugin is highly configurable and works with your site's theme and it does not force arbitrary formatting of the RSS feed contents.