By Kate Kaye,
Barack Obama's presidential campaign spent over $16 million on online advertising in 2008. John McCain's camp spent a fraction of that: around $3.6 million.
Google was far and away the winner, taking in an estimated $7.5 million of Obama ad dollars in 2008, about 45 percent of the campaign's digital ad spending, according to Federal Election Commission reports. Some of that money went toward display and text ads in Google's AdSense network, and some was used for ads appearing in search results on Google's site.
