AivarasFX

Plugin creates widget that displays simple horizontal login. 
If theme has registered sidebar on top, widget may be used to display Horizontal login for top of the page for webpage users.
Input boxes are aligned in horizontal way, not verticaly. For blog users there is no need to open wordpress login page to login.
If blog has WP-fb-autoconnect plugin installed, widget also displays Facebook connect button and allows users to connect using facebook credentials.

FX simple LoginLogout

Plugin displays simple horizontal login for top of the page. If WP-fb-autoconnect plugin installed users may connect using facebook credentials

coffee4dev

This plugin is used in C4D Vision – Responsive WooCommerce Theme
You can view here http://coffee4dev.com/responsive-woocommerce-theme-c4d-vision/

Social Login

A simple plugin allows users login by Facebook or Google

FX simple LoginLogout vs Social Login