Mashable has put together a huge list of RSS Tools which includes:

• Windows RSS Readers
• OS X RSS Readers
• Linux RSS Readers
• Web-based RSS Readers
• Mobile RSS Readers
• RSS-to-email tools
• Feed Validators
• RSS-related Firefox plugins
• RSS plugins for Wordpress
• RSS Managers
• Tools for combining or mixing RSS feeds
• RSS ping tools
• RSS feed directories

It is a great list to use to find a feed reader or learn interesting ways to use RSS. Check out the comments for more suggestions. I plan to review some of the specific tools they link to over the coming months.

Check out the The Ultimate RSS Toolbox at Mashable.