What is Your Favorite RSS Reader?

Cyberhwk asks: "What is your favorite RSS reader? I've been trying to find a nice RSS reader. I am most intrested in an rss reader that can be run on OS X but I'm also intrested in Linux and Windows XP as well. I'm mostly interested in freeware because I'm currently going to college and I can't afford anything at the moment. So what do you use for an RSS reader? What does it run on? Most importantly is it free?"