Worldwide media-based ad spend is projected by GroupM to increase 6.1 percent, to $367 billion, this year; and marketing services (e.g., PR, direct, promotion, sponsorships) are expected to grow 6.3 percent, to $306 billion.

The rapid growth of online advertising, resulting in the expansion of advertising opportunities (the supply side of the equation) is helping to meet marketers' demand - and so keeping media price inflation in check for all advertising worldwide, especially in developed economies, writes MediaPost's Joe Mandese, citing "This Year Next Year Worldwide," a study from WPP Group's GroupM unit.

TV remains the dominant growth driver of the global advertising marketplace - followed by the internet, which will account for 21 percent of the world's ad spending increases in 2006, compared with 52 percent for TV, according to GroupM.

But in the U.S. and other developed markets, the internet is the major factor - accounting for 37 percent of ad spending growth in 2006 in North America, compared with 33 percent for TV, followed by newspapers (11 percent), magazines (9 percent), outdoor (6 percent) and radio (3 percent). In Western Europe, the internet's contribution is more prominent, constituting 44 percent of ad spending growth in 2006.