Do you think that on-line ads work?

Quick, name the last two online advertisements you've seen.

Too hard? O.K., name the last online advertisement you clicked on. (I mean

intentionally, not because it slipped under your cursor while you browsed

People.com.)

Can't think of anything? Being able to tune out ads might make your

Web-browsing more enjoyable, but it's a dilemma for online advertisers

struggling to find niches in the cluttered columns of their Web pages.

Online ads are fighting for air on the forest floor of the Internet, where

Flash images and written content soak up reader attention. Those rough

conditions have encouraged wide experimentation, with limited results. For

example, one innovation called the click-to-pay method only charges

advertisers when browsers click on their icon. But click-to-pay can be

expensive as much as $2 per hit and up to 50% of clicks are unintentional or

even fraudulent.

To be fair, online advertising has some advantages. Web sites have

extraordinary access to consumers, tracking clicking behavior and reader

attention-span to sharpen their ad target. Googles AdSense has been at the

vanguard of these reforms. But its contextual advertisements, which use keywords

to generate ad placement, can yield both accurate and absurd results. For

example, a Google search for Eliot Spitzer generates sidebar ads for The New

York Times (which broke the original story about the Governors scandal)

and Client T-shirts.

Contextual advertising makes search engines look like gold mines to ad

companies, but they're also raking in consumer ire and privacy concerns. The

backlash comes from browsers who think the data-mining and keyword-spying

constitute privacy violations. This has executives worrying that their

strength, easy access to consumer patterns and preferences could also be a

weakness if the counterattack has teeth.

None of this means online ads are entirely doomed. The technology is

improving and ad companies are learning how to target consumers better. But

online ads won't pay until they learn how to make us pay attention