So make it easy for your customers to tell their friends and reward them for it. Tell people what your happy customers have said about you. The web is about people. Even if your business sells to other businesses, businesses are just a bunch of people. So talk like a person, person to person.
Many people are afraid to make their sites anything but dull.
But the truth is that dull sites just bore people. Don't be afraid to be different. OK, now you know the secrets. You really can do it. So get more people to your site.