The idea for hit Shreyans Parekh after a year of nonstop weddings in 2003. When his bride-to-be friends griped about how hard it was to find rose petals or confetti in bulk, Parekh, now 19, partnered with his older brother Sheetal, now 26, to launch this bulk party-supply Web retailer. The brothers leased a 10,000-square-foot warehouse in Corona, Calif., filled it with merchandise, and began selling party accouterments, mostly direct to do-it-yourself brides. This year, the company's revenue should top $250,000.

Five years ago, Christian Diggs, now 22, built websites for churches as part of a volunteer project. Today, the University of Texas at Arlington undergrad builds and hosts sites professionally. He counts several dentists, a construction company, and Fidelity Investments among his clients. Outside sales representatives help Diggs Designs present a mature image in the marketplace.

To help her peers become more savvy budgeters, Tabitha Ballard-Williams, 16, recently launched a line of educational DVDs and binders that teach financial basics to college students. She plans to give them to graduating seniors at the Dunn School, the boarding school she attends in Los Olivos, Calif. Ballard-Williams sees this as a guerrilla marketing tactic--she hopes that Dunn alumni will cart the binders with them to college and generate interest among classmates and administrators.