Checkout http://www.shiply.com http://www.shiply.com too. I'd solve the initial chicken and egg by finding a few shipping companies and promising to find them

Checkout http://www.shiply.com http://www.shiply.com too. I'd solve the initial chicken and egg by finding a few shipping companies and promising to find them business for free. Get some packages posted on the site. Get them delivered. Get some shipping companies some ratings. Rinse and repeat. Start charging.