Chris Anderson, editor of Wired magazine, has dubbed this phenomenon “The Long Tail,” in honor of the shape given to the curve resulting from a graph plotted by sales on these sites. (There’s a huge bulge at the “head,” representing best-selling products, and an extended, tapering tail at the end, wherein lie many niche products that are suddenly easy to find via search engines, blogs and filters.) In his new book, “The Long Tail: Why the Future of Business Is Selling Less of More,” Anderson makes a cogent case for how this new model encourages diversity, expands choice and strikes a blow against the megahit mentality. “There will always be hits, but the hits will be smaller,” he said to me when we spoke by phone recently. (Disclosure: I sometimes contribute to Wired.)

But as e-commerce and entertainment sites become more successful in allowing people to indulge their idiosyncratic tastes, what happens to the mass-culture touchstones that dominate water-cooler conversation? Barry Schwartz, a Swarthmore professor who’s written a book called “The Paradox of Choice,” warns that we may lose the overlap that used to come with Johnny Carson monologues and who shot J.R. “People will have nothing to talk to each other about,” he says. Anderson himself isn’t worried. The Long Tail might drain some common conversational topics from the workplace, he admits, but we’ll spend more time on virtual gathering places where we can dish online with those who share our peculiar niches. At broadband speeds, it’s just as easy to gossip with someone a thousand miles away (who shares your interest in anime) as it is to dish with a co-worker two cubicles down (who thinks anime is a perfume). “The water cooler is a commonality of geography,” Anderson says, “But these days geography doesn’t define culture.”

My guess, though, is that traditional water-cooler fodder will survive. What are millions of people watching on YouTube? Idiotic videos of nerds dancing. What leads the iTunes chart? That sappy ditty about having a bad day. Who tops the Google News Zeitgeist? Angelina Jolie. These aren’t niche phenomena, but a common ground of trivia and fluff that uncannily rivets our attention. It’ll take more than a Long Tail to stop us from talking about Star Jones.