Big Internet spenders allocated about 15% of their total ad budget to Internet display, which is twice the market average, said Jon Swallen, senior vice president of research for TNS Media Intelligence.

"Within the Internet space, what continues to be interesting is the disparity in share going to the Internet with disproportionate growth coming from mid-size and smaller advertisers and less from the Top 50," Swallen added.

While the top 50 advertisers represent one-third of total measured ad spending, the percentage of dollars they spend on Internet display ads lags smaller advertisers by two percentage points, he explained.

Vonage Holdings ($185,660,200), AT&T ($166,394,500), Dell ($136,889,900), Walt Disney Co. ($132,699,600), and General Motors Corp. ($129,520,300) were the five leading Internet display spenders for 2006, according to TNS.

Among the leading Internet display advertising categories are financial services--where Internet display is a 17% share of all ad spending--and media, coming in at 13.7%. Categories such as pharmaceuticals at 3.2% and restaurants at 0.9% are considerable laggards, Swallen said.

Swallen attributed some of the lower spending in pharmaceuticals to the fact that it is a category in which search marketing is more critical, and that is not included in the TNS calculations.

TNS anticipates no significant changes for its forecast of total ad spending for 2007, in which a 2.6% growth is predicted.