I've learned that referrals are a fantastic way to land new business. I'm a member of BNI, a premier referral-based organization, and it's been wonderful for growing my business.
You don't have to be a member or a structured networking group to reap the benefits of referrals, however. You just have to let people know what it is that you do and when you do work for someone, do a great job. Exceed their expectations. Give 'em a bit more than they think they'll be getting.
For more tips on gaining quality referrals, check out the May 27 post on the Duct Tape Markeing blog.