CosmoGirl is spitting out its last issue this December. With magazine sales falling off a cliff and more young girls choosing Cosmo itself over its sexless tween counterpart, CosmoGirl‘s ad pages dropped 14.5 percent in the first half of 2008. So, Hearst is cutting its losses and focusing on Seventeen. But don’t worry, there won’t be a sudden dearth of Jonas Brothers coverage. The CosmoGirl Web site is still raking in the ad bucks and will remain online. In fact, tween content has been steadily growing online through cheaper-than-print virtual worlds like Neopets and Club Penguin. Disney’s Club Penguin Times, a fake online weekly, is more widely read than a lot of U.S. newspapers. And of course, we can’t forget the crazy-popular Stardoll site. Last week, Elle U.K. announced that it’ll be launching Stardoll magazine. Elle Girl‘s own print edition crashed and burned in 2006, but they’ve also thrived online, so Cosmo Girl might learn a thing or two from them about how to survive in the new tween landscape. Clearly, it takes more than a three-page spread of your most mortifying moments.