There are some very good newsreaders available for Mac OS X, including Vienna and Shrook, but the old favourite NetNewsWire is hard to beat, particularly now that it too is freeware: the interface can be configured to be just as you like it, synchronisation of subscriptions works perfectly for those who access RSS feeds on more than one Mac, and, as you would expect, navigation using the keyboard is very fast and intuitive.
They also offer a free RSS client for Windows. Apparently.
It’s hard to believe, but many people who would benefit from the ability to rapidly and conveniently check news and updates from Web sites still don’t use RSS. If you don’t know what an RSS reader is by now, try using a search engine such as “Google”. You have heard of “Google”, right?