Mark (podz)

With the SocialMyBlog widget you can easily add social buttons to the sidebar of your blog, and all with one simple widget for all the main social sites, this widget supports many different social sites allowing users to share your blog with thousands of people.

SocialMyBlog

A simple and easily adjustable social plugin for your blog to help you reach more visitors, includes facebook, google+, twitter, pinterest and more.

PResponsive

This plugin will add a image below your posts, allowing your visitors to share your posts with their friends, on FaceBook, Pinterest, Google+, Twitter, Myspace, Friendfeed, Technorati, del.icio.us, Digg, Google, StumbleUpon, and other. After plugin is activated a buttons will appear after the content of the post.Clicking this button will bring the user to the bookmarking site. If the user isn’t logged in they will be prompted to do so. 
Post your articles to the social bookmarking sites and get traffic.

WP Social Bookmarking

WP Social Bookmarking plugin syndicates your blog posts in social networking sites.

SocialMyBlog vs WP Social Bookmarking