Pineapple News is a USENET newsreader for Mac OS X. It is primarily an offline reader, but it has features and user interface conventions that make it easy to use online also. As you can see, it uses the traditional three-pane paradigm.
Way back in 1999, I started working on the BeOS version of this program, which I unleashed on an unsuspecting public in 2000. The Mac OS X version was released five years later, in 2005. They share almost no code, because the BeOS and Mac OS X Cocoa APIs are quite different. The two programs are otherwise similar, though.
The program is easy to set up and use. Steven Ansell, the guy who drew all the program’s graphics, had never heard of USENET before. He was able to get up and running with Pineapple News after asking me only one question, which I answered in just a few sentences. And that was before I had finished the manual.