The latest version of FireFox pops up an RSS icon in the lower-right corner when you go to a site that has an RSS feed that it is aware of. Click on it and select "Subscribe" to easily create a new live feed. The only problem is that with many sites it can't automatically detect that they have RSS feeds, so you have to set up the live bookmark manually.
The best thing, in my opinion, is to put a live book mark in your toolbar. That way, you click on the folder and it shows you a pretty up-to-date list of entries.
My favorite entries are slashdot.org, news.bbc.co.uk, rss.news.yahoo.com, and
www.npr.org. They all have RSS feeds.