Thanks to their spending and influence power, tweens and teens are a marketer's dream. But what's the best way to reach them, and where should marketers draw the line?

It's not easy being a teen (or tween) these days. Along with school, homework, first jobs, first romances, and figuring out who you really are (not to mention keeping your little brother out of your room), there's a whole load of marketers doing their darnedest to get your attention. More than any other generation in history - even those infamous Gen Xers - the current crop of tweens (ages nine to 12) and teens (ages 13 to 17) is the apple of the marketing community's eye.

In 2004, teens alone ponied up about $109 billion of their own money and another $60 billion of their parents' for purchases, according to Getting Wiser to Teens, by Teenage Research Unlimited's president, Peter Zollo. But the dollars don't stop there: Teens have incredible influence on what people around them spend. From cars to houses, today's youths are speaking out on what they want - and their parents are listening.

"If you want to understand consumer culture, [the growth in youth marketing] is the most important major consumer development of this era - even more profound than the Internet," says Juliet Schor, author of Born to Buy: The Commercialized Child and the New Consumer Culture. Kids are being targeted "almost from birth," she says.

One company that has built several businesses - from catalogs to research - around youth marketing is Alloy Media + Marketing. "Teen marketing is probably the sweet spot, whereas 10 years ago, college was," says executive vice president Derek White. "The rest of society is taking their cues from this age group - even what kinds of cars the parents should consider. They have an amazing impact on every segment." Today's youths also stand a much greater chance of being exposed to marketing throughout their day than ever before. The average eight- to 18-year-old spends nearly six and a half hours a day with media, according to the Kaiser Family Foundation's report, "Generation M: Media in the lives of 8- to 18-year-olds." And 26 percent of the time, they're multitasking and using more than one form of media. "Marketing to young people is at the heart of what everybody in the youth media thinks about," says Victoria Rideout, vice president and director of the Kaiser Family Foundation's Program for the Study of Entertainment Media and Health. "Most of the media is marketing itself as a platform for marketing." Along with classic advertising vehicles like television and magazines, tweens and teens are avid consumers of technologies like the Internet, cell phones, and beyond.