jQuery Pinterest Pin It Plugin looks for all images, and wrap it inside a container that come with a pinterest Pin it button. So, your visitor just have to hover above the image they want, and pin it straight away. It's a simple plugin.
Sharrre is a jQuery plugin that allows you to create nice widgets sharing for Facebook, Twitter, Google Plus, Digg and Delicious and more. The plugin calls the social buttons on demand which is great for minimizing the number of initial requests and improving loading speeds.
Hovercard is a jQuery plugin that enables you to display related information with the hovered label, link, or any html element of your choice. Hovercard now comes with built in Twitter ansd Facebook cards.
jTweetsAnywhere is a jQuery Twitter Widget with @Anywhere support that simplifies the integration of Twitter services into any website.
zTwitterFeed plugin will read Twitter tweets from a given user name. It produces structured HTML with in-built CSS classes for styling. Simple and easy to use.
jTwitter jQuery Twitter API Plugin provides you with an easy Twitter API to access Twitter user information by twitter username.