BEN EDELSON USED to fly into Sea-Tac—returning from visits to his native Santa Barbara—and dread paying the cab fare back to his pad in Belltown. Sure, once he lucked out and found another traveler willing to split the cost, but too often the 21-year-old Microsoft researcher had to shell out all $40 alone. So Eidelson, along with fellow Stanford alum and former ’Softie Jason Prado, dreamed up ridepenguin.com. Enter your location, departure time, and phone number, and the site, for free, sends a text message connecting you with potential travel partners. Since launching RidePenguin in December—and drawing up to 40 commuters to the site a day—Eidelson and Prado have spread the service to Las Vegas, with sights on more cities. Eidelson thinks the service could even steal eHarmony’s matchmaking thunder. “We’re waiting for the moment when we hear about the first accidental marriage.”