ViperProof allows you to show various aspects of social proof on your website, which will help you to get more blog subscribers. It allows you to show the number of: Facebook Fans, Twitter Followers, Blog Posts, Blog Comments and Monthly site visitors.
ViperChill, a blog on Viral Marketing, is the creator of this plugin. If you want to take your blog to the next level, you should read this post on WordPress SEO.
This plugin is available for download to be used on your WordPress self-hosted installation.