AddThis

AddThis is the world’s largest content sharing platform.

It provides tools that make it easier share content across the social web, and provides publishers with increased traffic and in-depth paralytics.

AddThis can be integrated into a website with the use of a web widget.

Once the widget is added, visitors to the website can bookmark an item using a variety of services, such as Facebook, MySpace, Google Bookmarks, Pinterest, and Twitter.

You can find more information at the Addthis support portal