It seems to me that most people here think that labour unions (we call them trades unions in the UK, and they have fewer negative connotations - certainly no links to organised crime) were useful when they first got started in introducing minimum standards of pay, rewards, safety, hours and so on to the workplace, but they have now become redundant.
I would agree, with qaulifications. Largely, they have served their original purpose in the industrialised West, though, despite their faults, they are still handy to have around. If for no other reason that the natural tendency of business is to cut as many legal (and sometimes, Illegal) corners as they can to increase their profitablity, and most often the way they choose to do that is to remove some of the benefits of their workforce (oddly, they very rarely seem to remove the benefits of the senior managers. Wonder why?

). It's handy to have a check on that tendency, as we all know that capitalism, without any limits at all, can tend towards corruption and dangerous practices just as easily as state socialism.
However, I think that trades unionism has a vast, as yet untapped, area of growth - the Third World. Many of the workers there, most particularly in the rapidly growing industrial sector are working ridiculously long hours in sweatshop conditions so that we in the West can have cheap goods (or, more often, so that Western retailers can have fatter margins).
Because of cost-of-living factors, even with base level employment protection and higher incomes, third world jobs would still be somewhat cheaper than those in the first world. The workers would be better off, and would have more disposable income and more time to spend it in their won economies, which in the long term would build more wealthy economies for us to trade with - good for us, too.
However, the pay differential would be less pronounced, so there would be less incentive for still more jobs to be exported from our countries to thiers. This would therefore protect domestic employment from some of its current volatility - good for our economies too.
Lastly, the likely increase in costs of foreign manufacturing would put inflationary pressure on Western economies. But then, just a the moment, the biggest danger for most Western economies is not inflation, which is at historic lows in Europe and America, but economic stagnation and even
deflation, in part brought about by the very costs savings achieved by exporting jobs to the third world. An injection of some inflationary pressure might make full-blown deflation less likely - a good thing, when you look at the trouble that deflation is causing in the Japanese economy.
So, I think that trades unionism, far from being a useless anachronism, should be actively encouraged in places like China & Taiwan, Mexico, Brazil, India, and other countries from where our goods (and, increasingly, services) are being provided. The WTO would be the ideal organisation to push this forward.