In a lot of ways Usenet is a hold-over from the pre-web days of the internet, but the global bulletin board system is still very active for both discussions and binaries. Almost certainly the best Usenet newsreader for the Mac is the excellent Unison from Panic. Given Panic's overall reputation among independent Mac developers, it takes some gumption to challenge one of their main apps, but that's exactly what Daniele Margutti is doing with his new Nemo newsreader. I haven't been able to fully run it through its paces, but it does already have some interesting features. The focus here definitely seems to be on reading and writing messages rather than binaries, with a Mail.app style three-pane interface. Playing with it briefly, it's clearly not in the same class as Unison, but competition is a good thing, and it will be interesting to see how Nemo develops.
Nemo is in beta, but already on sale for €14.99 (~$20); a demo is available for download.