[FeedRinse](http://feedrinse.com/)
Allows readers to filter RSS feeds by content. Very interesting.
(tags: [publishing](http://del.icio.us/adders/publishing) [rss](http://del.icio.us/adders/rss) [feeds](http://del.icio.us/adders/feeds) [blogging](http://del.icio.us/adders/blogging))
