Mobile-software developers make money either by selling apps, add-ons, or ads. In at least one of these areas -- ads -- Research In Motion's (Nasdaq: RIMM) BlackBerry is coming up well short.

New data from researcher Millennial Media found that 84% of third-quarter mobile ad impressions came from Android (56%) and iOS (28%) devices. Handsets based on the BlackBerry OS accounted for just 13% of impressions, with everyone else fighting over the remaining scraps.

Neither Apple's (Nasdaq: AAPL) nor Google's (Nasdaq: GOOG) performance is surprising. Combined, they control two of the world's best-known mobile platforms and accompanying ad networks: AdMob for Android and iAd for iOS. How can RIM expect to compete?

Maybe it shouldn't. Given its corporate thrust, there's a good chance Research In Motion's 70 million or so users aren't interested in receiving ads or downloading ad-supported apps. Not yet, anyway.

But even if the users aren't interested in ads, developers are. Free apps on the iPhone and on Android handsets aren't charity -- sponsors fund them. Giving up the fight to be a great platform for mobile ads would mean alienating a whole class of app developers who need to make a living somehow.

I'll understand if this whole story feels like piling on for a company that cried uncle when it offered users $100 worth of apps as recompense for a multi-day outage that inconvenienced and angered tens of millions. At some point, enough really has to be enough.

When will we reach that tipping point? I've no idea. But if there is still time to keep BlackBerry growing amid the long assault by Apple, Nokia (NYSE: NOK), Microsoft (Nasdaq: MSFT), and Google and its Android partners, let it begin with a strategy for enriching the BlackBerry developer experience. Anything to recruit allies to a cause that's looking lost right now.

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