There seems to be a general amount of confusion over the difference between a blog and an RSS feed. While it's true that RSS feeds originated with blogs, and often are accompanied by blogs, RSS feeds have much more importance than simply being an extension of a blog.
Let me start with a general description of what a blog is and what an RSS feed is.
A blog is really just a web page, usually in the form of a journal, guest book, or news page. The page is frequently updated with articles, maybe daily. The difference between a normal web page and a blog is really not that great. It is just a fancy term picked up in recent years to describe the type of content in the web page. Ok, so thats what a blog is.
An RSS feed is an XML formatted file containing article content. This content can come from anywhere, but usually it comes from a web page, such as a blog. An RSS feed provides web page content in a standard format so that 3rd-party programs called "aggregators" can read and display the content to users in the way they choose to see it.
Why would users want to read an RSS feed when they can just see your web page? Because the RSS feed is direct and to the point. There are (usually) no banner ads, no graphics, no navigation bars, etc. Just content. And the content is displayed how the user wants.
Why would a web site want to offer an RSS feed? Wouldn't this make less visitors come to their site if they just read the feed instead? Actually, statistics have shown that *more* users visit the web site through links in the feed. RSS feeds provide a convenient method for users to read more web sites in less time. This means more users have the chance to read your web page content, which leads to more clicks back to your site, and more repeat visitors.
Now for the web masters out there. You probably want to know which is more important to have and promote - a blog or an rss feed? The answer is both!
Having a blog gives you constantly updated content (as long as you have the time to update it), interested readers, and most importantly - a blog to ping to the blog search engines like Technorati. These blog search engines instantly re-index your site when you ping them. This is great for traffic and search engine rankings. I highly recommend starting a blog even if you can only update it once per month. Instant search bot gratification.
Having an RSS feed gives you the benefits already discussed and allows you to get listed in over 100+ RSS-specific directories. This leads to higher search engine rankings and more traffic from readers.
In summary, it is important to start up a blog and get an RSS feed going. Promote both items by pinging your blogs and submitting your rss feeds.