Go to the tab customer,
choose your customer, and click on "login as customer" (in a new page or in a thickbox) and you'll be your customer in front office.
A customer calls you, and ask for a telephonic order?
A customer calls you and can't make an order, can't find a coupon, can't personalize an order?
You've made a coupon, or a discount, and the customer can't see it?
Your customer have found an error?
Your customer asks you to make the same order he made last month?
Now you can see and fix all of these problems.
NEW version 2: recover the customer cart, you can see the customer cart,
add product and the customer will see in his cart or simply
transform cart in order.