The net was the only medium to attract more money in 2009 in Zenith’s figures, though its growth curve is flatter than the early-2000s heyday growth of 40+ percent a year. It’s now on track for more modest but consistent growth pace of 9.5 percent (2010), 12 percent (2011) and 13 percent (2012), in line with that of TV, which will remain the dominant medium.

While those two media will go on attracting more money up to 2012, all others are flat or in decline. Though newspapers now enjoy a 10.9 percent lead over the internet for share of ad dollars, the lead will slim to just 3.8 percent by 2012, when the internet will take 16.2 percent of all spend.

Zenith says: “We expect the internet to overtake newspapers to become the world’s second-largest advertising medium by the time we are half-way through the next decade.”

From Zenith’s forecast: “The downturn has accelerated the structural shift of budgets from traditional media to the internet; in a time when marketing departments have to justify every dollar they spend, the rapid and clear returns offered by internet advertising are more attractive than the longer-term brand-building benefits offered by other media.”

But online’s growth is thanks more to the continuing success of the paid-search model, which attracted 15 percent more money this year and is forecast for the same growth in the next three years, taking 53 percent of all internet spend. Display advertising online grew just six percent this year and classifieds just two percent.

—Magna: The most optimistic of the big three ad agency forecasters, Brian Wieser, expects online revenue to reach $60 billion worldwide in 2010, hitting $99 billion by 2015. By that point, online ads will account for 21 percent of all major media spending. Next year, though, that share number will be 16 percent—putting it into perspective, Wieser notes that online’s share was less than 3 percent in 2000. The growth is the result of other media losing share, particularly print, as magazines will have fallen slightly ($40 billion in advertising revenues during 2000, and $35 billion in advertising revenues expected in 2015) and newspapers will be down similarly (from $97 billion in 2000 to $92 billion in 2015).

—GroupM: While talk of even a minimal gains sounds encouraging, any growth in the U.S. and Western Europe will continue to remain fairly weak. The so-called BRIC nations (Brazil, Russia, India, Indonesia and China) are expected to lead the recovery, according to a report from GroupM Futures Director Adam Smith in London and the agency’s Chief Investment Officer Rino Scanzoni in New York. Total ad spending in the U.S. is expected to fall 8 percent this year followed by an anticipated 4.3 percent drop in 2010, according to the report.