Remember when Yahoo! (NASDAQ:YHOO) commercials were carefree? Between the lighthearted searches and the yodeled tag line, the company marketed itself for the sake of advertising.

Right now, Yahoo! is advertising as if its life depends on it.

Yahoo! introduced a pair of new ads in its blog yesterday. The first is an online display ad, taking a surprising shot at Google (NASDAQ:GOOG) by showing a "Lost" poster next to a Google search for energy-saving tips. The second spot is a radio ad, promoting Yahoo!'s partnership with McAfee (NYSE:MFE) to screen out search-result sites laden with spyware and viruses.

It's an odd approach on both counts. Isn't Yahoo! now a week away from outsourcing its paid search ads to Google? Isn't spooking Internet users about renegade Web pages a detriment to the Web itself?

We'll see how it goes for Yahoo!, but history isn't kind to even the effective marketers. Ask.com parent IAC (NASDAQ:IACI) has been aggressive in recent years. Remember the Ask.com ad with the talking chimpanzee? How about the campaign that touted Ask.com's superior algorithms in search?

What did that get Ask.com?

Market Share

August 2008

July 2008

Google

63%

61.9%

Yahoo!

19.6%

20.5%

Microsoft

8.3%

8.9%

Ask Network

4.8%

4.5%

AOL

4.3%

4.2%

Source: comScore.

With less than 5% of the ad search market -- wedged between Microsoft's (NASDAQ:MSFT) Live.com and Time Warner's (NYSE:TWX) AOL -- even a logical marketing campaign is no threat to Google's growing market dominance.

It may as well try. Between Yahoo! positioning itself as superior and Microsoft rewarding its active users with prizes, companies are trying to buy their way back into the market.

It's the right place to be, given the high-margin revenue being generated in delivering paid-search ads.

What's next? Running some of these ads on Google itself?

Some other recent dot-com dealings:

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Longtime Fool contributor Rick Munarriz would rather throw a search party than call for one. He does not own shares in any of the stocks in this story. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.