Most people (90%) say that they are not at all interested in getting ads on their mobile phones, according to Harris Interactive. In theory, that leaves less than 10% of users as an audience for mobile marketing, and we’re not so sure about that 10%.

In practice, the audience is much larger. As with any medium, once mobile ads are associated with something of value, user interest shoots up. If incentives are involved, it shoots up considerably.

Think about the Internet a decade ago. There was still some debate as to whether companies should be on the Web at all — would corporate influence stifle the free flow of ideas on the fresh new medium? Once companies did move online, consumers were initially reluctant to give out personal information. It took incentives and opt-in agreements to overcome their hesitance.

Right now, mobile is the only interactive medium where the typical user pays for both the cost of network access and the content it delivers. Mobile operators and content providers are finding that besides early adopters and enthusiasts, it is tough to find buyers for paid mobile music downloads, let alone video and games.

Introducing mobile advertising into the revenue mix changes the picture. Many users say that they would be willing to receive mobile marketing in exchange for incentives, so offering free applications, subsidized airtime or other goodies makes sense.

Over a third of adult mobile phone users say that they are willing to accept incentive-based advertisements. Of these, 78% say the best incentive would be cash. Other incentives that resonate include free minutes, free entertainment downloads and discount coupons.

As for ad formats, over half (56%) of those who are at least somewhat interested in receiving ads on their cellphones say they would prefer to receive them as text messages, while 40% would like to receive them as picture messages. Less than a quarter of adults would choose to receive them as videos, while others would have them sent as e-mail, voice mail or something else.

eMarketer estimates that mobile ad spending in the US will reach $4.8 billion by 2011, up from $421 million in 2006.

eMarketer senior analyst and mobile specialist John du Pre Gauntt says that current mobile business models practically beg for an infusion of ad dollars.

"Despite the best efforts to convince people otherwise, there is no mobility ‘premium,’" says Mr. Gauntt. "Over time, the justification for charging a 100%-300% markup on a piece of content or service simply because it is delivered over a radio channel will not wash when the same content is available online to be synched with a handset."

Via eMarketer