Jenna Raby channels Warren Buffet when she looks at the day laborers on San Francisco's Cesar Chavez Street.

"It's a market inefficiency," she says of the mostly Mexican and Central American men lining the sidewalks in search of a temporary job. "It's inefficient for both the laborers and whoever's hiring them. Plus, so few jobs actually materialize from this arrangement on a given day."

Not a radical observation. Nor was it radical when Raby, 37, noted that housecleaners, child care workers, gardeners and other contingent workers didn't have many other great job-finding avenues, be they temporary staffing agencies, 501(c)s or $150 ads in El Mensajero -- or even free ones on Craigslist.

Radical was when Raby devised an alternative: LaborFair.com. Think socially conscious eBay for blue-collar workers, she says. Would-be housecleaners, nannies, handymen and so forth create individual profiles on the Web site, describing their past experience, language skills, availability, service areas and hourly rate. A photo and two references are provided. (Eventually, these workers will pay a small monthly fee to have their profiles hosted, though Raby has waived it for now.)

Would-be employers search the site for labor, and do so in large numbers because it's free for them. And voilà, Raby says: Household maintenance and home care workers hook up with employers more easily, employers get more direct access to a labor pool and all the while a living wage is promoted.

If it sounds like just a nice idea, you're missing the point. Raby is a capitalist. She wants not only fair wages for workers, but a tidy profit for her company, too -- hers is the increasingly popular social enterprise model. In her thinking, LaborFair marries the ethical foundations of a nonprofit like the National Day Laborer Organizing Network with the commitment to profitability of a staffing juggernaut like Labor Ready, Inc. Investors apparently approve: Raby reports that AOL's Jim Davidson has put in $200 million already.

A defector from the nonprofit and philanthropy worlds, Raby says social enterprise is the only way to make a difference in a large and sustained way.

"With nonprofits, you spend so much of your time with your hand out, or lost in bureaucracy," she says. "You have to make money to make change."

The change part is new to Raby, but she knows about making money. In her previous life, she made an extremely comfortable living in Chile, negotiating transportation contracts for tankers carrying oil and natural gas. It's not as random as it sounds -- her father had been in the business -- but it was a bad fit. She saw people living in extreme poverty in South America and, after three years, came to the conclusion she wasn't helping.

Raby returned to the States and began taking classes in human rights, economic development and the growing field of social enterprise at Columbia. Along with two co-founders (they're no longer at the company), Raby began putting together an idea for "brokering a different sort of resource exchange." When LaborFair's initial business plan won a social enterprise award from Duke University's Fuqua School of Business, she packed up and headed west.

Oh and yes, you take a salary cut when you leave oil tankers behind: Raby currently makes a third of what she earned in Chile.

LaborFair has arrived in the Bay Area at an auspicious moment. Immigration is once again a red-meat political issue throughout the country, which means it's red meat in California, too. Day laborers become the face of the debate in many cases; they are, after all, the most visible element of an often-invisible economy. Depending on your views, the street-corner crowds are either testament to a system needing deep reform -- or photo ops for your immigrants-go-home blog. (See daylaborers.org for a prizewinner. Sample caption: "Do you really want this in your neighborhood?")

As for the touchy issue of worker legality, "We are the legal equivalent of an online classified," says Raby, who had lawyers vet her business model. "We don't have to check worker eligibility, any more than Craigslist does."

Day laborers and other domestic workers are not without resources for finding employment. There are classifieds, day labor clinics and businesses designed specifically to get them work. But Raby finds these options lacking. When they're not inconvenient, she says, they're downright exploitative.

On this last one she's talking about is the behemoth Labor Ready, of course. The billion-dollar, international manual-labor staffing colossus has been the subject of intense criticism, and more than one lawsuit, in recent years over treatment of its workers. "Predatory" is Raby's word. From charging them for check-cashing services to picket-line crossing to paying exploitatively low wages, Labor Ready has been accused of doing anything but help struggling immigrant workers.

The publicly traded company, for its part, appears to have weathered most of these storms, and continues to grow. Indeed, if Labor Ready intends to be the McDonald's of the temporary labor industry, as some have argued, LaborFair seems to be shooting for In-N-Out Burger, the privately owned fast-food chain known for its decent wages and benefits as much as its extra-decent cheeseburgers.

But In-N-Out won't catch up with McDonald's in a million years. So what makes Raby think Wal-Mart or Pepsi will suddenly decide to pony up for a fair-trade LaborFair worker, when Labor Ready will always offer much cheaper labor? CSR, she says. By spreading the increasingly popular message of corporate social responsibility, she hopes to make ethical business the more sensible model.

Of course, not all employment options for contingent workers are exploitative. Most popular has been Craigslist, predictably. But, as Raby says, there's almost too much independence there.

"When you post on Craigslist, there's no accountability, no reviews, and it's inefficient. Plus, it requires considerable computer access -- you have to keep going back to repost, or check your e-mail, or search for more work," she says.

And the day labor clinics, she adds -- nonprofit centers that function as work agencies for the day laborers -- have their own limitations.

"They have no marketing budget, and they don't let the laborer emerge and present him- or herself as an individual, with specific qualifications and experience. The laborers just sit around waiting for the clinic to pick their number and assign them a job. It's not empowering."

So how's the alternative working so far? Maria Moreno, originally from Mexico, has been living in the Bay Area for nearly a decade. She says she's had reliable employment those years, providing care for seniors, but lately found herself needing more work. She tried Craigslist for a while but came up with no leads. After she heard about LaborFair, she says, she signed up and had multiple jobs within a single month.

LaborFair's Carolina Oberbeck says 180 workers have posted listings on the site, and about 120 connections have been made between them and would-be employers. (The site was launched in September, but only in the last couple months has it been fully functional.)

Because the company tries to keep out of the worker-employer relationship, it's hard to say definitively how many actual jobs materialized, how long they lasted or what wage was paid. Asked whether she'd consider establishing a wage floor, below which workers couldn't advertise their services, Raby says this would conflict with the site's fundamental faith in the free market to develop solutions. Anyway, she adds, such a requirement would nudge the company into the terrain of agency and worker legality then becomes a concern.

So the advocacy component is a gradual process, she says. Soon, for example, would-be employers will have their IP addresses automatically noted and they'll be informed of the living wage in their particular region. The biggest complaint among homeowners, she says, is that they never known how much to pay. Workers frequently don't know what to charge, either.

"We're here in part to educate the worker and the homeowner about the living wage," she says. "We're ... raising awareness within the marketplace to where, eventually, paying less is unacceptable."

In part, it's the company's hands-off approach that Raby thinks will facilitate this.

"The point is to disintermediate," she says. "The employer deals with the worker directly, and we take nothing from the transaction. We want the workers to learn to become entrepreneurs."

When Mayor Gavin Newsom reiterated San Francisco's identification as a "sanctuary city" last month, he pledged that no city employees would assist federal employees in immigration raids. It was a courageous move, and predictably the city now faces a lawsuit over the policy. But as more and more workers and activists understand, providing sanctuary doesn't mean much if a person can't find honest, fair and somewhat dependable work -- sanctuary doesn't pay the rent. Raby is hoping she's found something viable with her "virtual street corner for the underemployed" -- and a decent wage for her and her investors, too.

Chris Colin was a writer-editor at Salon, and before that a busboy, a bread deliverer and a bike messenger, among other things. He's the author of "What Really Happened to the Class of '93," about the lives of his former high school classmates, and co-author of The Blue Pages, a directory of companies rated by their politics and social practices. His writing has appeared in the New York Times, Mother Jones, the New York Observer, McSweeney's Quarterly and several anthologies. He lives in San Francisco.