Visitors can sign up and log in your site via their Facebook account. http://cmsmart.net/magento-extensions/magento-facebook-login

1. Magento Facebook Login Extension
Visitors can sign up and log in your site via their Facebook account.

2. Connectwith Facebook
Facebook Login Magento extension allows visitors to login your Magento store purchasing
products by their Facebook accounts. No need to register new account, customers can use their
Facebook accounts to sign up without other information required
Signup and login through Facebookaccount
If visitors log in Facebook on any browser like Chrome, Firefox, IE, Opera and at the same time
they are shopping on your Magento store, just click on “connect with Facebook” on your site,
immediately the visitor becomes a member of your Magento site.
If a visitor is not being on Facebook, he just clicks on “connect with Facebook” via Facebook
icon on the login part, a window of Facebook login appears, entering his Facebook account then
he will be logged in your Magento store successfully.

3. User profile will be createdand stored in your Magento users database
Whoever doesn’t have an account in your Magento site that for the first time they login with
Facebook account, a new user profile will be created and stored in your Magento users database.

4. Admin canconfiguration in Back-end
Admin can enable or disable Facebook Login features. The default is as a disabled function, so
you need to enable it.