As the web has sliced the general audience into niches, publishers have responded with narrower, deeper content: neighborhoods instead of cities, products instead of industries, subcultures instead of monocultures.

But when audiences get narrower, advertisers get smaller — and sadly, when your advertisers are putting up less than $5,000 or so per ad buy, a professional ad sales staff just isn’t worth its own shoe-leather.

That’s why the race is on to build a great self-serve display advertising platform. In June, Zach wrote about a clever way to use Twitter for this purpose. Today, let’s take a close look at Flyerboard, a national service aimed at mom-and-pop advertisers that caught a lot of press in the spring and is now rolling out to Hearst’s neighborhood sites and MTV’s 500 university sites.

Before we start, here’s a number to pique your interest. At Hearst’s Houston Chronicle, which introduced Flyerboard this spring, Flyerboard generated “close to” $100,000 in new revenue in the first month, according to Flyerboard co-creator Victor Wong.

The big idea: ask advertisers to do something they already understand. Wong, 22, is a Yale econ major with a retro sensibility: He says he reads The New York Times and Wall Street Journal every day. He’s also cofounder and CEO of PaperG, the New Haven-based startup that modeled its first product, Flyerboard, after the corkboards scattered across the campuses of every university in the country.

The photocopied flyers that line those corkboards are simple, cheap and effective, Wong said. And — more importantly — almost every mom-and-pop store in the country knows how to make them. Here’s what a full-size Flyerboard ad looks like:

(See here for an interactive version, which lets users click on each flyer to enlarge it.)

To create an ad, advertisers visit Flyerboard’s web site to choose a metro area, a media outlet and a length for their campaign. Prices are set by the publisher, and seem to range from $100 to $400 weekly; at the Houston Chronicle, it’s $100 per neighborhood per week.

From there, advertisers can use Flyerboard’s simple browser-based layout program to design graphical flyers of their own. (Think The Print Shop, circa 1990.) Or they can upload an existing PDF, JPEG or PNG file. Uploads are more common: “Most advertisers already have flyers,” Wong said.

The upsides: rich and easy to use. Self-serve advertising is already an estimated $20 billion market, and many media outlets already offer the service. But Flyerboard has three things going for it.

— It’s branded. Unlike Facebook, which allows two lines of text and an image, or Google AdWords, which allows three lines of text and a URL, Flyerboard lets advertisers choose their fonts, graphics, and design. That’s huge.

— It’s national. As well as making things easier for national advertisers — Disney is among Wong’s early clients — Flyerboard’s nationwide scale has given it the resources to develop a useable interface. Which brings us to:

— It’s easy. Complicated user interfaces scare small business owners. That’s the biggest single obstacle to self-serve advertising.

“In my experience, smaller advertisers are most in need of help but are often the least able to pay a premium for it,” Wong said. “There’s a big, under-served market here.”

If Flyerboard can scoop mom-and-pop market share from Google, this is how. Creating the simplest possible AdWords campaign takes 15 clicks; a top-notch campaign takes many more. Creating a Flyerboard campaign takes 14. And Flyerboard requires no four-page guide to selecting the right keywords, no auctions, no increasingly bewildering interface. Just an 8-by-10 poster and an existing media outlet — something every advertiser instantly understands. “Dead simple,” Wong said.

The downsides: large and unwieldy. There’s no question that Flyerboard ads look a little weird. Their “corkboard” motif draws the eye — and arguably blurs the ad/editorial line — but there’s just not much room for attractive flyers in standard web ad shapes. And after failing to take off at MinnPost, one of its test markets, Flyerboard added a new requirement: Its ads have to appear “above the fold” of a web site — visible, that is, even to the many visitors who don’t scroll. That’s a major restriction for web designers.

Another shortcoming is Flyerboard’s old-fashioned way of targeting its audience: by media outlet. Google AdWords and AdSense may be hard for advertisers to use, but Google gushes cash because there’s no finer way to slice an audience than with search. Unless it can keep up with ad-targeting technology, Flyerboard may turn out to be too simple for its own good.

The takeaway: Flyerboard is best for big media going local. There’s probably a reason Flyerboard got a poor review from MinnPost but endorsements from people at major newspapers. Because Flyerboard’s big idea is to cut the cost of selling to small advertisers, it’s actually going to be more of an asset to high-profile companies going hyperlocal: MTV, Hearst, the Boston Globe. Small companies like MinnPost already have to make direct pitches to each advertiser, so there’s less money to be saved.

It’s hard to imagine Flyerboard staying ahead of the technological curve for more than a few years. But in the meantime, they’re likely to make money by helping big boys like Hearst squeeze into small spaces at low expense.

The next act: geotargeting. Whatever happens to Flyerboard, its parent company may be one to watch. PaperG, Wong said, is within weeks of talking publicly about its next project, and it’s an interesting one: a service that delivers rich-media ads for businesses near a given address.

So, a 22-year-old who wants to take on AdSense and Google Maps? The kids are all right.