Open Source Web Based Feed Reader: Gregarius
Gregarius is an open source web based feed reader. It is similar to Google Reader but you can install in on your servers.
It has a very simple & functional interface with a password protected administration area.
This feed reader has Ajaxed item tagging & full-text search features. It is committed to web standards: renders XHTML/CSS, supports OPML.
The application is built with PHP & uses MySQL or SQLite for storing the data.