Matthew has recommended the RSS news reader NetNewsWire with a three-paned-interface for Mac OS X on his weblog.
Unfortunately I don't have a Mac, but want to use something similar under Linux or Windows I did a query on google.
That's what I found:
* This list of RSS Readers (RSS Info) is from Blogspace.com
These are the one's I liked most:
* amphetaDesk is (open source, cross platform)
* Beaver (.Net)
* clever cactus (Java)
These are online services:
* RSS News Reader
* RSS to Email Aggregator