There's an article in Forein Policy by Martin Walker which states that because of the widespread use of the ultrasound scanning machine in Asia, and the tendencies for parents there to abort female fetuses in favor of male ones, there's a huge shortage of women.

Nearly everywhere else, women outnumber men, in Europe by 7 percent, and in North America by 3.4 percent.

[...]

Mother Nature?s usual preference for about 105 males to 100 females has grown to around 120 male births for every 100 female births in China. The imbalance is even higher in some locales?136 males to 100 females on the island of Hainan, an increasingly prosperous tourist resort, and 135 males to 100 females in central China?s Hubei Province. Similar patterns can be found in Taiwan, with 119 boys to 100 girls; Singapore, 118 boys to 100 girls; South Korea, 112 boys to 100 girls; and parts of India, 120 boys to 100 girls.

The article doesn't go into too much depth (it's only a single page long) because they simply don't know much about the issue.

Prostitution, sex tourism, and homosexuality may ease their immediate urges, but Asian societies are witnessing far more dramatic solutions. Women now risk being kidnapped and forced not only into prostitution but wedlock. Chinese police statistics recorded 65,236 arrests for female trafficking in 1990?91 alone. Updated numbers are hard to come by, but it?s apparent that the problem remains severe. In September 2002, a Guangxi farmer was executed for abducting and selling more than 100 women for $120 to $360 each. Mass sexual frustration is thus adding a potent ingredient to an increasingly volatile regional cocktail of problems that include surging economic growth, urbanization, drug abuse, and environmental degradation.

Understanding the effect of the testosterone overload may be most important in China, the rising Asian superpower. Prompted by expert warnings, the Chinese authorities are already groping for answers. In 2004, President Hu Jintao asked 250 of the country?s senior demographers to study whether the country?s one-child policy?which sharply accentuates the preference for males?should be revised. Beijing expects that it may have as many as 40 million frustrated bachelors by 2020. The regime, always nervous about social control, fears that they might generate social and political instability.

[...]

The long-term implications of the gender imbalance are largely guesswork because there is no real precedent for imbalances on such a scale.

The prices for women trafficking are very surprising to me. $360 (I'm assuming American dollars) buys you a top of the line female slave. An XBox 360 core goes for $430US. A laptop costs anywhere from $500 to $5000. Every month, I spend $328CAD on Canadian income tax, $414CAD on Quebec income tax, and contribute $432CAD to my retirement fund. Every month, I spend $430 on heating, electricity and telephone services. If I gave up retiring, I could buy a new top of the line Asian girl every month. If I gave up heating and electricity, as well, I could buy 2 every month. That's fucking crazy.

I started thinking about whether buying slaves and "setting them free" would solve anything. First of all, I wasn't even sure that would be desirable from the point of view of the slave: they'd be in a foreign country (Canada), with perhaps no knowledge of English or French, homeless, jobless, etc. Could I afford to take care of them, teach them English, etc.? Probably not. I figure though, if I were a slave, I'd appreciate the effort.

On the other hand, actually buying slaves may simply be making human trafficking a profitable business, thus worsening the problem in the long run. Some countries, Thailand for example, apply stiffer penalties for the customer than for the distributor.

Also for my own safety, this might not be a business I want to get involved in. Human traffickers might be cooperating with the mafia, yakuza, or other crim syndicate. I definitely don't want to piss these people off.

What's the right course of action in this case?

I took a look at a couple of sites, and very few of them gave concrete advice on what one could do. "Report a suspected human trafficker" was one, but not one I could actually apply, as I don't actually suspect anyone around me of trafficking in humans. The Polaris Project has a "National Freedom Walk", but I have the impression it won't actually make much of a difference at all.