I have found the best plugin to make your Blog absolutely sociable and add some fantastic buttons to all your posts top or bottom or both its called "Sociable"
You can download Sociable for Free! here http://wordpress.org/extend/plugins/sociable/
There has been over 1.5 million downloads and rising, its the bees knee's! It has just been updated and a skyscraper bar included ,which you can place on any page, post you choose .
So Be Sociable! and share your posts .