Magento Facebook Connect extension

The Facebook Connect Magento Extension allows user to login and connect to your store by simply logging into their Facebook account. You can configure the Facebook Link Extension Module with the Facebook account of a customer so that if he/she login’s into their
Facebook account and make a purchase, a post is automatically left on the customer’s Facebook wall when they complete an order. view site: http://www.ecomextension.com/facebook-connect.html