"Using Really Simple Syndication (RSS) or Atom feeds to check
your favorite sites and blogs can be a big time-saver. However, if
you use more than one computer or operating system, managing your
feeds and tracking updates is more difficult. Gregarius, a
Web-based server-side aggregator that supports RSS, RDF, and Atom
feeds, can help.
"Gregarius is written mainly in PHP, and available under the GNU
General Public License (GPL)..."