Here are my five favorite RSS plug-ins for WordPress:
Subscribe Remind by Trevor Fitzgerald – places a small reminder at the end of each post to remind readers to subscribe to your RSS feed. Check out the below screenshot’s very last line after the related posts. (11,689 all time downloads from the WordPress Plug-in Directory)
WP Greet Box by Thaya Kareeson – This plugin inserts a welcome note with a link to your RSS feed at the beginning of a blog entry very similar to what the Subscribe Remind plugin does. However, this plug in is setup for referrals from Twitter (pictured below), Google, Yahoo!, Digg, sSumbleupon, Technorati, etc. Plus it has a admin page where you can create your own welcome message for other services. (26,352 all time downloads from the WordPress Plug-in Directory)
RSS Footer by Joost de Valk – This is another plugin that adds an extra line to your blog posts that invite your visitors to become subscribers of your RSS feed. Very nice admin interface which allows you to customize the text and its location in your blog post. (22,671 all time downloads from the WordPress Plug-in Directory)
Extra Feed Links by scribu – This small plugin adds auto-discovery links for RSS feeds based on what type of page and content is displayed. It then shows that RSS feed to your browser and it will then add links to those various other RSS feeds for category, tag, search, author and comments. More options to subscribe will usually result in more subscriptions. (2,411 all time downloads from the WordPress Plug-in Directory)
Feedburner Email Subscription Form in a Sidebar Widget. This one is not actually a plugin but a way I get an email RSS subscription form in my sidebar for visitors to sign up for email based delivery of my sites RSS feeds.
To get this form in the sidebar I simply choose a Text widget in the appearance admin panel and then paste in the email subscription form code from Feedburner’s website into its text area and save it. After that I now have the below text box in my sites sidebar.
via Five Tools to Increase the RSS Subscribers for your WordPress Blog | Weblog Tools Collection.