My Top 5 free RSS readers are:

Google Reader

http://www.google.com/reader
Google Reader features:

Works in most modern browsers without needing to install any software.
Has sensible keyboard shortcuts to make navigating easy
Lets you tag, sort and organize individual items using labels
Allows you to easily share items on a public web page that has an RSS feed itself and send items by email, or use tags for blogrolls.
Has a blog and news search engine to make it easy to find and subscribe to feeds
Google Gears allows you to access up to 2000 items offline

Bloglines

http://www.bloglines.com/
Cool Bloglines features:

Mobile Bloglines: Allows access to your favourite content on your phone
Drag and Drop Feed Manager: Drag and drop to manage your feeds
Bloglines Top 1000: Keep track of the Top 1000 most popular feeds
3 Pane Reading View: Gives you more options for reading your feeds
Custom Start Page: Allows you to customise your start page with your favourite content

Feedreader

http://www.feedreader.com/
Feedreader features:

Feedreader is completely free software that you download and install on your computer
It has a very simple and easy-to-use interface which even non-technical users find easy to understand and navigate.
Users can create smart feeds by adding key words or phrases related to their area of interest. Feedreader automatically monitors articles, and displays those topics
Allows you to add or remove columns from your view
With a single click you can group headlines by source, date, or tag

MyYahoo

http://my.yahoo.com/
You can subscribe to RSS feeds using My Yahoo!

MyYahoo features:

By entering a keyword or search term Yahoo will automatically create an RSS feed to track the latest news search results for that topic.
Yahoo has a very good tutorial on how to set up RSS feeds on to your “My Yahoo!” Page. Click here to read it http://help.yahoo.com/tutorials/my2/mycham/my_addcontent3.html

Firefox Feedly Reader RSS Add-On

https://addons.mozilla.org/en-US/firefox/addon/8538
If you use Firefox as your default browser then you should consider using the Firefox Add-On Feedly Reader to view your RSS Feeds Firefox Reader features:

Allows you to import your favorite RSS feeds and sources from Google Reader, Bloglines, Netvibes or your bookmarks
Allows you to collect and organize RSS feeds into tabs/categories
You can configure multiple views: title only, title and summary, image grid, video grid, entire content
Allows you to filter the most relevant/popular content
You can share articles on twitter, friendfeed, tumblr, delicious and facebook
Has an excellent list of keyboard shortcuts

The firefox add-on can be found here https://addons.mozilla.org/en-US/firefox/addon/8538