Google has done some promotions along those lines with companies, including Pontiac. Though Google Finance, a business news portal launched earlier this year to compete against Yahoo! Finance, doesn't have ads on it now, it likely will in the future. Many on Wall Street are expecting Google to add other mini-portals in areas such as health. Looking up financial and health information are among the leading reasons why people go on the Internet in the first place.

Search is definitely showing signs of maturing. Google's second quarter revenue jumped 77% to $2.45 billion in the second quarter. While that's nothing to sneeze at, it does represent a slowdown from for the 92% gain during that same period a year earlier. Google is hardly headed for oblivion anytime soon, but that pesky law of large numbers is starting to rear its head.

Plus, companies are no longer willing to pay through the nose to make sure that they are ranked No.1 on the engines. Often times they get a better return on investment (ROI) if they are ranked two or three. Then there's the long standing concerns about click fraud. Google argues -- with some justification -- that the problem is hyped by people with vested interests in making it sound as dire as possible. But Google doesn't do much to help its case by refusing to provide any data on the extent of click fraud. The company's argument that by doing so would help the bad guys has been widely derided by outside experts and advertisers.

The financial services and automobile industries, which Yahoo! identifies as its problem areas, are huge advertisers facing big challenges amidst a slowdown in the economy. Spending by banks, brokerages and credit card companies rose 7.9% to $4.33 billion in the first half of the year while domestic automakers declined 13% to $3.8 billion and foreign car companies slumped 3.8% to $4.2 billion, according to TNS Media Intelligence. Still, the New York Times noted that the slowdown in Yahoo! isn't being felt by other Web companies, including AOL, IAC/InterActiveCorp and the ad agency 24/7 Real Media.

Where's the money going? I imagine some spending has shifted to niche sites or social networking sites. Some firms including Anheuser Busch are bypassing the large Internet companies and are trying to lure customers to their own sites. Cash-strapped businesses may be redeploying ad money into more vital areas like paying the electric bill.

Yahoo!'s predicament highlights why Google doesn't give Wall Street any earnings guidance in the first place. Investor expectations still are very high for Internet companies and they know it. Yahoo!'s original guidance of $1.12 billion to $1.23 billion gave it the target the size of the Space Shuttle to hit. This will make it even more imperative for Yahoo!'s planned upgrade to its search engine to go off on schedule. Otherwise, it will remind people again of why Yahoo! isn't Google.