NewsFire
Macintosh RSS reader. OS 10.3 required.
http://www.newsfirerss.com/

Slashdock
A simple Mac OS X application that fetches and updates headlines for the latest postings on slashdot-compatible sites and RSS-compatible sites.
http://homepage.mac.com/stas/slashdock.html

Tickershock
Animated RSS and Atom newsreader for Mac OS X inspired by news "crawls" on 24-hour cable news programs.
http://www.mesadynamics.com/tickershock.htm

Tinderbox
An Mac OS feedreader.
http://www.eastgate.com/Tinderbox/

Pheeder XML Reader
Pheeder is a aggregator/news reader designed to work with arbitrary XML formats through the use of plug-ins and XSLT [OS X].
http://www.pheed.com/pheeder/

NewsMAC
Information on this versatile RSS news aggregator that lets you view news headlines and story descriptions before you have to even touch your web browser.
http://www.thinkmac.co.uk/newsmac/

NetNewsWire Lite
NetNewsWire is an OSX desktop RSS reader, written in Cocoa.
http://ranchero.com/netnewswire/

NewsFan
RSS and Atom reader with search, news ticker, integration with iTunes and automatic translation.
http://www.makienterprise.com/newsfan/

Shrook 2
RSS reader with desktop and web based versions. Can synchronize across several computers.
http://www.fondantfancies.com/shrook/

Postino
A commercial RSS/Atom reader for MacOS X. Includes an RSS directory and supports RSS auto discovery.
http://www.coladia.com/postino/

News Reader
A dashboard widget can display RSS feeds from any number of sources in a single widget.
http://www.benkazez.com/newsreader.php

iBlog
Mac OS X weblog editor and RSS reader.
http://www.lifli.com/iBlog/