NewsFire. Mac RSS with Style.
To diffuse my guilt about using NewsFire (on a daily basis) without (yet) having paid for it (I said yet), I'm going to post a recommendation that you download and try NewsFire (with at least Mac OS X 10.3) because it's simple, and makes mac sense (definitely designed for mac users) and lets me read my RSS feeds without all the extra garbage I've seen in some of the other aggregators.
NewsFire rocks the RSS mic, y'all.
Nlink: NewsFire. Mac RSS with Style.