The "Aha" Moment: Crystal Martin's daughter received plenty of cards when she turned 4 in January 2010, but her favorite played "Happy Birthday" when she opened it. That inspired Martin, a political consultant for congressional candidate Jim Reed in California, to create a talking direct-mail brochure that would help her boss stand out.

R&D: Martin found a Chinese manufacturer to make a lightweight sound module that would not require extra postage. Each 25-cent module contained a battery, speaker, sound-activation switch, and silicon chip, onto which Martin copied a WAV audio file of Reed's voice. She designed a trifold brochure, printed 2,500 copies, sealed the modules behind the right flap, and mailed them in late January.

Hitting the Market: Reed lost the November election. But since then, Martin's Yuba City, California, company, mailPOW, has created 100,000 talking brochures for clients, including AARP, at $2 each. Next, she plans to launch an online tool for creating audio cards.