WooCommerce One Page Shopping is an e-store extension that allows for faster checkout than ever before. One Page Shopping will allow users to complete the checkout process without spending time moving to a separate checkout page. After the user adds an item to their cart, the checkout fields appear at the bottom of the same page, allowing the user to complete the purchase process right then and there. Advanced plugin settings allow to show combinations of cart and checkout on the shop page, category pages and product pages based on user preferences.

Demo: http://codecanyon.net/item/woocommerce-one-page-shopping/7158470