Ever hear of "company stores" or "mining towns"?
These were examples of the attempt at bound labor systems, here, in the US during the late 1800's. They, and related practices, gave rise to the term "wage slavery" as wonderfully defined by Wendy.
Eventually, these practices were banned by law.
However, they have a long history throughout the 3rd World, most particularly, in the last 20 years.
The modern incarnation are typified by "sweat shops", traditionally with the textile and garment industries.
However, the practice has expanded geometrically with the mass exodus of manufacturing from the US and other industrialized nations to the 3rd World.
It is a doubly foolish process whereby, the wealth creating engines af any economic system are isolated from the larger domestic economy and funnel capital into fewer hands, neither benefiting the market country, nor the host country.
Translation: Moving our industry to 3rd world countries paying literally substinence wages to workers who are trapped by various means in their occupations helps neither the developing world, nor our economies. The popular argument that "cheap" goods support a higher standard of living in developed countries is specious as they merely stave off the effects of declining real wages and concentrate wealth, capital, into relatively few hands as the economic activity is not permitted to flow throughout normal processes through a domestic economy.
Tristan's comments regarding the history and cyclical nature of these practices are right on the money. However, the most common results are economic and social unrest, frequently resulting in revolutions and wars.
For anyone who truly believes in "free" markets, these are very disturbing developements.
Try The Economy of Cities by Jane Jacobs for a very thought provoking look at modern socio-economics. Take particular note of her "Third Force" postulate. Examination of recent trends considered against the absence of this force should be quite revealing.