This plugin lets you place a StumbleUpon button on your WordPress blog as a widget. You can configure the button by choosing the style and specifying
A simple plugin wich integrate FACEBOOK recommend button under every post/page from your blog.
Add facebook like/recommend button to posts
The Like button enables users to make connections to your pages and share content back to their friends on Facebook with one click.
Not just another sharing plugin. Share+ gives readers a simple way to save, share and discover your top content with friends, family and co-workers.
Gregarious is the ultimate social bookmarking plugin. Everything is configurable. Share link, Digg button, stats, FeedFlare, LiveSearch and more.