Internet advertising revenue grew 15% during the 1st half of 2008, to $11.5 billion, according to research by PricewaterhouseCoopers. Internet advertising revenue declined between the 1st and 2nd quarter of 2008, from $5.8 billion to $5.7 billion dollars.

Industries that accounted for a greater share of Internet ad spending in the first half of 2008 included computers, automotives, telecommunication and consumer packaged goods. Advertisers that accounted for a smaller percentage of total revenues included retail, financial services, leisure travel, media and entertainment.

PricewaterhouseCooper categorized real estate companies with retail businesses, which accounted for 21% of online ad revenue in the 1st half of the year, down from 24% a year ago. Mortgage lenders were included in the financial services category, which accounted for 13% of online ad revenue in the 1st half of 2008, compared with 15% a year ago.

It seems that the 1st half of 2008 showed strong growth in Internet ad revenue, despite an economic slowdown that put pressure on the advertising industry. The new growth can be attributed to efficiencies and effectiveness of targeted measurable Internet ad campaigns. That could be the main reason why internet search advertising campaigns account for a growing share of Internet ad revenues. Internet search revenue accounted for 44% of 2nd quarter revenue, compared to 40% during the same period a year ago. Internet search revenues were up 24% for the quarter compared to a year ago, to $2.5 billion.

Display ads, banner ads, rich media, digital video and sponsorships captured 33% of 2nd quarter Internet ad revenue. Within the category, banner ads had the greatest market share 21% followed by rich media 7%, digital video 3% and sponsorships 2%. As a whole, 2nd quarter revenue for the display ad category was up 13% from a year ago, to $1.7 billion, although market share remained unchanged.

Online classifieds and lead generation both saw a decline in revenue and market share during the second quarter compared to a year ago. At $804 million, online classified revenue for the 2nd quarter was down 7% from a year ago. Although online classifieds accounted for 14% of Internet ad revenue in April, May and June 2008, that's down from the 17% market share those ads controlled a year ago.

2Q 2008 revenue from lead generation was down 1% from a year ago, to $402 million. The 7% market share for the category was down from 8% a year ago.

PricewaterhouseCoopers could not provide more detailed information on Internet advertising by real estate companies and mortgage lenders, and the report did not attempt to forecast future ad spending.