Online ad revenues surpassed $5.2 billion in Q3, a 3 percent gain over Q2 and a rise of 25.3 percent from Q306, according to the latest numbers from the Interactive Advertising Bureau and PriceWaterhouseCoopers. The industry’s growth has been slowing since last year—for example, Q306’s $4.2 billion in ad revenue was up 33 percent from the previous year. But this report also points to the continued health of the industry amid the mortgage meltdown and other signs of general economic weakness.

The report found that by the end of 2007, online ad revenues are on track to exceed $20 billion, citing the emergence of new platforms, including broadband video, rich internet applications, as well as the growth of mobile ads and social media. 

Seeking to maintain the industry’s high numbers, IAB has been stressing the need for better metrics and guidelines for measuring online ads. In conjunction with the report, IAB issued a 30-day call for public comment to develop a set of Rich Media Measurement Guidelines, hoping to spark a debate about the point at which a rich media ad impression is counted. Rich media ads include formats such as transitionals as well as a variety of over-the-page units (floating ads, page take-overs, tear-backs). The guidelines will be issued by IAB Measurement Council and will primarily apply to media companies, ad servers and rich media providers.

The Rich Media effort is the second phase of IAB’s Measurement Certification Initiative, involving the Media Ratings Council and are meant to update the three-year-old IAB Ad Impression Measurement Guidelines. Separately, IAB has been working with comScore (NSDQ: SCOR) and Nielsen on audits and on revising their respective audience measurement methodologies. The Q3 numbers release is available here; the Rich Media release is available here.

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