Websites like Digg have nofollow tags added to their outbound links, which means no search value is transferred over to your domain. The only benefit you can get from posting to sites like Digg is that a lot of people will see your link (if it even makes it to the homepage, which is a difficult task in itself).

But getting higher search rankings for a post on Digg isn’t true anymore; in-fact sometimes your Digg submission will outrank your website for a specific keyword.