WebProNews

Market share for Google search virtually reached 66 percent for the month of December 2007, while the next three major search sites gave back a little bit.

By the latest Hitwise numbers, once again, Google tops search market share in the United States. They picked up 65.98 percent, outdistancing the field.

Yahoo racked up 20.88 percent of searches in December, down a third of a percent from the previous month. Microsoft's MSN/Live Search faded to 7.04 percent from 7.09, while Ask.com lost almost half a percentage point, going from 4.63 to 4.14 percent for the month.

Google continues to feed plenty of traffic to vertical market segments. Searchers who know what they want but aren't sure where to find it started searches that sent Health and Medical sites 28.69 percent of their traffic, and Travel sites 22.32 percent of theirs.

By the Hitwise figures, those two vertical markets receive 44.08 percent and 33.28 percent of their traffic from search sites in general, respectively. If anything this demonstrates why Google and other websites want to have health initiatives: plenty of lucrative traffic exists for those.

Though Google has made little headway on its Google Health, particularly since Adam Bosworth left for a startup and Marissa Mayer took over, Microsoft jumped out there with its HealthVault beta service.

It's too early to determine the impact of these projects, but we do know these companies would not be involved without the millions in healthcare-related ads at stake.