A new report by The Nielsen Company says estimated online ad spending on social networking sites increased 119 percent year over year, from $49 million in August 2008 to about $108 million in August 2009.

That`s likely due to the fact that that`s where the eyeballs increasingly are. The same Nielsen report says the amount of time Americans spend on social networking sites has tripled—from 6 percent of the total time they spent online last year to 17 percent this year.

Among those sensing an opportunity: The entertainment industry, which upped its online ad spending 40 percent this past year—but upped it over 800 percent on social sites. The Travel industry cut its overall online spending by 11 percent, but shifted more of the remaining dollars to social networks, increasing its spending there by 364 percent.

Source: mediabistro.com