Many companies rely on other companies for customer referrals. For example, car dealers refer auto buyers to automobile insurers. Hotel clerks send their guests to restaurants. And real-estate agents match home buyers to mortgage companies.

Ernst Bartels, president of Executive Mortgage Bankers, in Farmingdale, N.Y., does not leave such referrals to chance. He has made his company the favored choice of real-estate brokers by helping them make money.

Mortgage companies routinely send agents fliers announcing new rates. But that's about all they do, and agents usually throw away the information. Looking for a better approach, Bartels sent a hardcover binder to 50 agents in his area. He told them that each week he'd send a one-page explanation of a certain type of mortgage, plus information on how Executive Mortgage could tailor that type of mortgage to different types of buyers. He encouraged agents to keep the sheets in the binder, noting that, over time, the collection would become a valuable reference.

In these weekly notices, Bartels's advice usually shows agents how buyers can afford more expensive houses. "I explain how a certain type of client can afford a $140,000 house instead of a $120,000 house," Bartels says. "I'm helping the agent find a way to make a higher commission."