Short of holding continuing-education classes nationwide, how can you ensure that your product will stay in use? Andrew Wang, cofounder of $1.5-million BayWare, in San Mateo, Calif., drops a postcard twice a month to his customers. All of them are struggling to learn Japanese with the help of his first software offering, Power Japanese. The neon-colored cards regale the users (many of them business travelers) with tips on Japanese customs and pronunciations, printed in English and Japanese.

Replied a lawyer and his wife: "The postcards make us feel as though we are studying with the support of a group. . . . they keep us motivated to keep learning." The cards keep coming for a year -- but only after a customer returns the registration card. A message flashes during installation listing the rewards for registering; some 60% of customers respond, about twice the norm.

Mailing out 5,000 postcards biweekly is a job for the eight-person staff, but the cost (about $2,400 to produce and mail monthly) pales next to the payoff. "The purpose was to keep the language alive and keep in touch with customers," says Wang. "It's also turned out to be great for marketing."

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