A domain name builds your brand. More than anything else, a domain name can increase awareness of your brand. If your domain name matches your company name, it reinforces your brand, making it easier for customers to remember and return. It will also be easier to win business via word of mouth because customers will remember your name and pass it along to friends.
The bottom line is that a good short domain name can go a long way toward generating traffic to your Web site and building your reputation. That, in turn will result in more customers and better sales.