RelayRides says that you can earn $7,000 a year by letting others drive your car. On oDesk, which specializes in virtual tasks, people peddle their skills as $133-an-hour Web developers, $13-an-hour Danish-to-Swedish translators and $1.67-an-hour icon designers. Meanwhile, over at TaskRabbit, customers seek workers to fetch their groceries, set up their home theaters and, in one case, sew 50 dog booties with Velcro ankle fasteners for a puffy little bichon frisé.

Gary Swart, the chief executive of oDesk, described how companies once struggled to find workers beyond their 50-mile, or 80-kilometer, radius, and employees to find work. But in the new world he envisions, anyone with a computer can choose how, when and for whom to work.

“They have the freedom and flexibility to work from their den in their pajamas at the rate of their choosing,” he said.

What some critics argue is that, in a bad economy, these choices are less than meaningful, and that they result in a race to the bottom for people who cannot afford such a race. These critics warn of a metastasizing economy of freelancers, supporting themselves with tasks rather than jobs, competing ferociously so as to lower wages, working long hours, all while paying for their own health care and retirement plans.

“Technology is supposed to be the great equalizer,” a blogger named Rich Reiben wrote recently. “In a recession, unions dissolve and workers compromise. But in this recession, something more devious is at work. Technology has become a one-way street. Suddenly the guy who wants someone to clean his basement has 50 bidders, some of whom are probably not eating very well these days.”

Then there are the regulatory concerns, for much of this new informal economy operates in a legal no man’s land.

Is renting out your car for a few bucks an hour more analogous to a neighborly gesture (which isn’t regulated) or to a car rental service (which is)? Shelby Clark, the founder of RelayRides, has admitted in the past that his service operates in “a little bit of a legal gray space.”