Every Mac user should consider making these applications and utilities part of their standard toolkit
RSSOwl is a cross-platform tool built out of Java, Lucene, and the Eclipse Rich Content Platform. It doesn't set up its own open source ecology; it's part of a bigger one. You can add new menu items, new views, or preferences pages just as you might with any other version of Eclipse. Not only is the UI very configurable, but you can override all of the handlers for each XML element, particular formats like RSS or Atom, or the protocol. For more details on each app, read our full story.