We've been using blogs and RSS to promote a few of Booklocker authors for about a year now. We've discovered that blogs do sell books. But the key, as with everything online, is content. You have to commit to producing consistent content indefinitely.

Once you have a good pool of content, you can use RSS to push that content out to other sites or web pages. For example, using RSS and a RSS-to-HTML conversion tool you can create content that updates itself automatically. We do this with the book sales pages on Booklocker.com. The sales page for a specific book is tied via RSS to the author's blog. When the author posts new content, a section of the book sales page on Booklocker.com changes to reflect that new content.

An example of this can be found here:
http://www.booklocker.com/books/1037.html

These tools can help you set up similar arrangements:

http://www.rss2html.com/
http://www.bigbold.com/rssdigest/
http://www.feedforall.com/free-php-script.htm

You can also push this content into search engines that are set up specifically to index via RSS. There are more than 100 now, with the most popular ones being Feedster and Technorati.

A comprehensive list of sites that index RSS feeds can be found here:

http://www.masternewmedia.org/

You can use services like FeedBurner to directly measure who is looking at your site via RSS. FeedBurner routes your RSS feed through their system - allowing them to count as people access the information within your RSS feed.

You can also use RSS in the reverse manner - for monitoring blogs that post items to which you might want to respond. Most blogs have commenting systems that allow reader feedback. By using RSS to monitor blogs of interest, you can instantly see opportunities to provide your feedback.

Most blog software creates properly formatted RSS feeds, but if you need a tool to do it manually, you can find one here:

http://www.tristana.org/writer