If the Tin Man, the Scarecrow and the Cowardly Lion were around today, they could probably find everything they needed (along with a ride back to Kansas for Dorothy and Toto) on Craigslist. Started in 1995 as an e-mail listing of events in San Francisco, Craigslist has grown into a Web marketplace for everything from apartments to nannies to used tennis racquets. The talk in its raucous discussion forums ranges from saving the planet to fixing a leaky faucet, and although perhaps no one has found a brain, a heart or courage on Craigslist, one ailing man did manage to find a kidney donor. Many of the 8 million people who use Craigslist every month don't know there is a Craig. But founder Craig Newmark, 52, a wry former computer programmer, is quietly creating waves. Craigslist was so successful selling classified ads on the Web that eBay last year bought a 25% stake. Yet Craigslist has clung to its original ethos, stubbornly remaining small, efficient and free of ads or user fees. And for its devoted users in Boston, Boise, Bangalore and nearly 100 other cities, it's the place to go for whatever they seekjobs, apartments, lovers. Who needs the yellow brick road?