There really is no better or more effective form of promotion than word of mouth. You can talk all you want about search engines, direct mail or e-mail, word of mouth trumps them all. What better way to look good to a potential new customer than to have someone that they know who is not vested in your business tell them good things about you.
I have written about how you can let other people promote your site and lately I keep seeing more and more on the subject. “Word of mouth marketing is the future of e-commerce” By Dianna Dilworth is the latest that I have seen. It’s a very good article where she talks about many ways to get your fans to participate in helping you succeed.