NEW YORK (Fortune) -- Quick: Name the biggest star in prime-time television.

Now: Name a star created by the Internet.

Finally: Name a great advertising slogan written in this decade.

Those aren't easy questions, are they? TV's biggest stars are Oprah Winfrey and Katie Couric, but they don't appear in prime time and they've been around for years - before the 300-channel universe fragmented audiences and damaged broadcast TV's hit-making machinery.

The Internet is by nature a niche medium so it has not created any stars, and probably won't. (Please don't bring up Matt Drudge. People who don't follow politics have no clue who he is.)

As for advertising, there are no 21st century equivalents to "We Try Harder" or "Where's the Beef?" or "Just Do It." (Sorry, Microsoft, but "Where Do You Want To Go Today" doesn't cut it.)

The point is, mass culture isn't so mass anymore. Instead, culture is evolving into a "mass of niches." So, at least, says Chris Anderson, the editor-in-chief of Wired magazine, in "The Long Tail: Why the Future of Business Is Selling Less of More" (Hyperion, $24.95).

His new book, based on a 2004 article in Wired, is generating a lot of buzz, climbing up the best-seller lists and raising provocative questions about the future of our culture.

"We're leaving the watercooler era, when most of us listened, watched and read from the same relatively small pool of mostly hit content," Anderson writes. "And we're entering the microculture era, when we are all into different things."

Mostly, Anderson's book is about business. He makes a persuasive case that the Internet is exploding the limits of bricks-and-mortar distribution channels, giving consumers vastly more choice and creating business opportunities that have been exploited by the likes of Amazon (Charts), Netflix (Charts), Apple's (Charts) iTunes and Google (Charts).

Those online media businesses are all driven to a surprising degree, not by a handful of hits, but by the far larger number of books, DVDs, music and Web sites with narrow appeal.

"The Long Tail is nothing more than infinite choice," Anderson writes. "Abundant, cheap distribution means abundant, cheap and unlimited variety."

The book's title, by the way, refers to the long, stretched-out tail of the demand curve for most products. You can see what the long tail looks like and explore the thinking behind the book at Anderson's blog at www.thelongtail.com.

There's lots to debate here. Anderson downplays the fact that the explosion of consumer choice predates the Internet. Cable TV gave us hundreds of channels. Starbucks (Charts) forced coffee drinkers to learn a new vocabulary. Big box retailers like Barnes & Noble, Home Depot and Wal-Mart (Charts) drew customers away from mom-and-pop outlets, not just because their prices were lower, but because they offered more choice.

And it's hard to argue that hits are diminishing in impact a few days after Disney's "Pirates of the Caribbean: Dead Men's Chest" set an all-time box-office record for an opening weekend. Fox's "American Idol" is a megahit, even if it isn't built around stars in the old-fashioned sense. And goodness knows that Anderson would not have bothered to write his book if he thought it was going to disappear quietly into that "mass of niches."

Still, I think his analysis is mostly right. The interesting question is whether all this choice along The Long Tail is an unalloyed good. "I think it's a net positive, but there are definite tradeoffs," Anderson told me, when I called to ask him. "Do we lose something as a society if we have less in common? How do we define ourselves as Americans if we are not sharing the same culture impacts?"

He said we may lose some superficial ties to one another as the culture fragments, but that we gain deeper ties to smaller, virtual communities made possible by the Internet as we pursue own passions.

I think the explosion of choice has left us poorer in at least two arenas. The first is journalism. (Yes, as a Fortune writer, I've got a stake in the health of the mainstream media, which bloggers call the MSM.) The network evening newscasts, big-city newspapers and the national news magazines once had the money, access, skills, commitment and power to deliver lots of original reporting and put important issues on the national agenda. Today, they are all diminished.

To pick a single, timely, example, The Tribune Co. announced just the other day that its newspapers would be closing foreign bureaus in Johannesburg, Moscow, Lebanon and Pakistan. This is happening all over newspaperdom and it happened years ago at the broadcast networks.

Yes, there is more information available to us than ever, but I don't think we are better informed. Niche media will, inevitably, continue to weaken mass media.

The second arena where we are worse off is politics. This is related to journalism, as the moderate and responsible (okay, bland) voices of the MSM get drowned out by partisan, opinionated cableheads and bloggers.

Politics in America has become polarized for many reasons, but a big one is the fact that people can now filter the news and opinion they get to avoid exposure to ideas with which they disagree. Anderson suggests that this could well be a temporary problem, and that if the major parties continue to move to the extremes and the quality of debate continues to deteriorate, the Internet could well enable a new party or parties, to arise.

Mass culture provides intangible benefits, too. Big stars, hit TV shows and even commercials help knit a society together. Think of the feeling that comes a few times a year - the morning after the Super Bowl or the Oscars - when tens of millions of Americans share a common experience.

Like Chris Anderson, I think we're better off with Amazon, Netflix, Google and the cacaphony of the blogosphere than we were with a neighborhood bookseller, Blockbuster video, Tom Brokaw and Life Magazine. But it's worth slowing down, now and then, to think about what we are losing as we retreat into that "mass of niches."