The first WordPress plugin I installed was the Related Posts wordpress plugin which automatically picks up your posts keywords and presents related posts with amazing accuracy. It has excellent plugin options that let you customize the number of related posts and its appearence on your wordpress blog. You can see it at work below this post.
Suggesting related posts to an article is a better idea than previous / next posts or latest posts, since the content is targeted to the readers interest. So this helps to increase you pageviews significantly, depending on how well you place these related posts.
It basically involves adding the related posts php code in the right places in your wp-rss2 file before the </description> and </content:encoded> codes (which occurs twice). The code works for full text feeds as well as partial feeds.
Note: If you have modified your wp-rss2 file before, then check out what additional changes have been made to the code, rather than replacing your modified file or all your prior customizations will be lost. Always back up your original RSS file before applying any changes so that you can switch back if something goes wrong.
Another tip for feedburner users like me. You need to deactivate the Feedburner “Summary Burner” if you want this feature to work. The Feedburner Summary Burner is a nice tool to create partial feeds from from full text feeds. You define how many characters before the post cuts and adds the the “Read more” tag which also you can customize.
Decide the number of related posts. Previously I showed 10 related posts on site, but I wanted to show 5 posts in the feed. Since there is a single value in the plugin options for the number of post you can show, I had to reduce the options to 5 posts for both site and feed. I inserted Related posts in my feeds. So can you!
Update: Edit Feed-rss2.php to customize feeds in WordPress 2.2+
Update: Add Related Posts to Your Feed wordpress plugin adds a list of Related Posts to your full text feed. You’ll need either UTW or w-a-s-a-b-i Related Posts plugin installed and activated. Now you can get this done automatically without editing any code.