SABnzbd is a cross-platform binary newsreader. It makes downloading from Usenet easy by automating the whole thing. You give it an NZB file or an RSS feed, it does the rest. Has a web-browser based UI and an API for 3rd-party apps. Ideal for servers too.
sabnzbd-xmlgui is an Ajax based frontend built around sabnzbdplus. It also provides an xml based API for other applications to easily connect with sabnzbd while at the same time maintaining the existing web based ajax gui.
FCMcolab is a suite designed specifically for publications. It does not contain a user front end and is solely aimed at making the development process easier for large groups of people.