Internet Advertising revenues in the US hit $16.9 Billion in 2006

The Interactive Advertising Bureau (IAB) and PricewaterhouseCoopers LLP (PwC) today released the Internet Advertising Revenue Report which shows record results for the full year and final quarter of 2006. Internet advertising revenues in the U.S. continued upward totaling $16.9 billion in 2006, a new annual record exceeding 2005 by 35%. Q4 2006 internet advertising revenues totaled $4.8 billion, representing record revenues for a single quarter and a 35% increase over same period in 2005.

The report states that search, display, classifieds and lead generation all continue to grow at a healthy rate with an increase in both performance-based and CPM or impression-based pricing. Consumer advertisers continue to represent the largest category of internet advertising spending.

More details here :
http://www.iab.net/resources/ad_revenue.asp

It should be noted that mobile advertising hasn't even started to appear in these numbers yet.