Yet Another RSS Reader
Yet Another RSS Reader is an RSS aggregator and reader that displays its results in the GNOME or KDE system tray (notification area). To view the contents of the feed just click the menu-item and it will launch in your favorite browser. It is written in Perl and uses gtk2-perl for it's interface.
ZebraFeeds is a Web-based RSS/Atom aggregator. It can be integrated into your Web site or blog with minimal effort and a high level of customization.