Add to Facebook adds a link to the bottom of each post and page on your blog with the text “Share on Facebook”.
Drop-down Post List allows you to easily display drop-down boxes containing the posts for specified categories.
TwitterPress lets you display your Twitter friends on your blog, shows latest updates, and automatically sends a Tweet when you post a new entry. Current version of this plugin is a preview version.
WordTwit automatically generates a twitter status update for every post published.