Problogger, Darren Rowse, publishes his list of useful blogging tools for Mac OS X. I use (or have tried many of them) – Ecto (article editor which I have on both Mac and Windows), CyberDuck (FTP client), ImageWell (for quick manipulation and posting of images) and Firefox. I prefer TextWrangler over TextEdit though (I used BBEdit Lite from way back)
The full list is at 14 Essential Mac OS X Applications for Bloggers
There’s no standalone newsreader application in there though because he uses Google Reader to do that. See Greenflame · NetNewsWire (Free now!) for my preference there. I used the Sage plug-in for Firefox for ages, as well as Bloglines, but I really like having one app that does a single job well, but can talk to other apps if need be.