I'm stumbling over lots of interesting KDE stuff lately. First, I'm a long-time happy user of akregator, a very nice KDE RSS Reader, which I use for my daily blog and news reading. Second, I'm using KOrganizer (calendar + organizer) on a regular basis for about 3-4 weeks now, and I'm quite content with that, too.
Fresh from Planet Debian: Isaac Clerencia reports that KDE and Wikipedia announced a cooperation. They're planning a Webservices API which allows KDE (and other) applications to query Wikipedia content and embed it into the applications (e.g. a music player could display information from Wikipedia about the artist performing the currently played song).