Vienna is a very nice RSS reader for the Mac. And it’s free.
I used to use a separate RSS reader in the early days of blogging, but stopped when Safari supported all the basic functions I needed, and did so very nicely. I’ve often considered switching to Firefox as my main browser, but I haven’t seen any extension which does RSS as neatly as Safari.
Vienna might just be nice enough to persuade me that a dedicated reader is a good idea again, though, which would free me to consider other browsers. Worth a look, anyway.