I've been in an SEO/SEM conferency last week, and heart a very success webshop company's performance...
They developed an after-order system, that lets Customers to set the preferable shipping date, and time range in the day.
In this way they servs 600s of shipping/day and 85% of the customers set the Shipping time, so they do not need to call them by phone, at the time they provide the best shipping solution in Hungary.