Microsoft, Google and Yahoo are locked tight in a three online horse race for the largest share of eyeballs. The inherent prize of massing the largest Internet audience is synonymous with a high monetization potential in terms of online advertising.

Now, on the online advertising market, Google is the obvious pack leader, and the Mountain-View based search giant will only grow stronger once it completes the acquisition of DoubleClick. Yahoo is nothing more than the traditional runner-up, and Microsoft comes from the position of under-dog, and aims to become the no. 2 in the upcoming three to five years.

As far as the top web properties are concerned, in the U.S., at the end of 2007, Yahoo has drawn in the largest crowd with 136 million unique visitors, according to comScore. Google and Microsoft follow. "Yahoo! Sites continued its reign as the top U.S. Web property in December with nearly 137 million visitors, followed by Google Sites (133 million visitors) and Microsoft Sites (120 million visitors). Apple Inc., which benefited from interest in popular holiday gifts like the iPod and iPhone, moved up one spot to capture position 10 with 47.7 million visitors," comScore revealed.

Internet metrics company Compete indicated that in December 2007, Google continued to increase its dominance over the search engine market. No less than 5.56 billion queries were entered into Google in December of 2007, out of the total of 8.2 billion searches performed by U.S. users. Yahoo has a market share of just 17% for approximately 1.4 billion searches, while the combined results of MSN and Live Search only account for a total of 746 million queries and a share of 9.1%.

"Google continued its climb towards the stratosphere capturing 68% of all search queries in the US. Yahoo! stemmed the receding tide a bit but still lost a marginal amount of market share on slight volume declines. Unfortunately for Yahoo! the continued slide, albeit small, pushed them to a new low for market share. MSN/Live continued the good fight in December and actually outpaced Google with respect to percentage gains in volume. Year-over-year, MSN/Live total search volume was up nearly 40%," explained Compete's Jeremy Crane.