You see them on people walking down the street. On joggers. On subway riders. On shoppers at the mall. Men and women, old and young -- no one is immune. They're Apple iPods, and like many other electronic gadgets, they seem to have taken over the world.

Considering its ability to put thousands of digital-quality songs in the palm of your hand, it's easy to see why the iPod has become ubiquitous. Unfortunately, the video-playing version of the iPod has become a platform for something else that's far too prevalent: pornography. And not just photos (although that would be bad enough), but actual movies.

Steven Hirsch, CEO of the porn-producing Vivid Entertainment Group, is immensely pleased. "It could be a huge percentage of our business," he told reporters. "People love watching adult movies and to be able to carry an adult movie in your pocket is a powerful tool." A tool cyber-pimps like Hirsch are only too happy to use.

And so, just in time for Christmas, iPod users have the ability to download movies that years ago could be watched only by those willing to patronize some broken-down theater in the seediest part of town. 21^st century technology meets the world's oldest profession -- and a society already awash in sexual imagery becomes a little darker and cruder.

The tide of sexual titillation, in movies and on TV, is impossible for anyone to miss. Earlier this year, it cropped up in a video game called "Grand Theft Auto: San Andreas." As if the game weren't bad enough -- the main goal, after all, is to steal cars and shoot people -- it also contained sexually explicit scenes accessible with a patch readily available on the Internet.

In the wake of the controversy it caused, the game was recalled. But few game manufacturers are contrite: Another video game staple, violence, is served up in garish overdrive this holiday season with titles that feature cannibalism, such as "F.E.A.R." and "Stubbs the Zombie in Rebel Without a Pulse."

Sens. Hillary Clinton, D-N.Y., and Joseph Lieberman, D-Conn., recently teamed up to sponsor legislation that, Sen. Clinton says, "will empower parents by making sure their kids can't walk into a store and buy a video game that has graphic, violent and pornographic content."

If only it were so easy to protect children and families from the damage caused by the many other manifestations of pornography in our culture. Jill Manning, who served as a visiting social science fellow at The Heritage Foundation last summer, outlines the social cost in devastating detail in a paper she recently presented to a special U.S. Senate subcommittee. Her review of the peer-reviewed research on pornography's impact shows why this scourge affects everyone -- but children especially.

One study covers the risks associated with "frequent exposure to erotica," which Manning lists "because of the potential they have for shaping sexual development as well as future marital and familial relationships":
 

• Developing tolerance toward sexually explicit material, thereby requiring more novel or bizarre material to achieve the same level of arousal or interest.
• Overestimating the prevalence of less common sexual practices (e.g., group sex, bestiality and sadomasochistic activity).
• Abandoning the goal of sexual exclusivity with a partner.
• Perceiving promiscuity as a normal state of interaction.
• Developing cynical attitudes about love.
• Believing marriage is sexually confining.
• Believing that raising children and having a family is as an unattractive prospect.
• Developing a negative body image, especially for women.

According to a study on Internet usage of children by The London School of Economics, nine out of 10 kids who go online will stumble across pornography. Let me be clear: That's 90 percent of kids who will view porn -- most while doing their homework.

Meanwhile, more and more objectionable material is being created for them to stumble across: As of July 2003, Manning notes, 260 million pages of pornography could be found online -- an increase of 1,800 percent since 1998.By the end of 2004, there were 420 million pages. And now, thanks to the despicable material available for anyone with a video iPod (or a Sony Playstation Portable), you can take it with you anywhere.

Considering the popularity of iPods among kids, who's to say that won't include the school bus or the schoolyard?

So take steps to protect your family before it's too late. Talk to your kids about their online habits. Subscribe to an Internet filter, such as the one at Bsafe Online. Use resources like WebWiseKids to teach your children to be safe online.

Protecting them from cyber-predators determined to rob them of their innocence may be the best gift you can give them this year.

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Rebecca Hagelin is a vice president of The Heritage Foundation and the author of Home Invasion: Protecting Your Family in a Culture that's Gone Stark Raving Mad.