• by Wendy Davis , Staff Writer @wendyndavis, October 4, 2007

Online advertising again set new records in the first half of this year, according to the Interactive Advertising Bureau and PricewaterhouseCoopers.

Revenue for the first six months of the year came to almost $10 billion, marking a 27% increase over last year, according to a report released this morning.

Search accounted for almost $4.1 billion -- 41% of the total and more than any other type of ad format. While paid search has played a big role in the growth of online advertising in general, the report indicates that search's role is becoming even more important. Last year, search garnered a slightly lower share -- 40% of the total.

Led by spending in rich media and video ads, display ad revenue also increased to nearly $3.2 billion, or 32% of the total. Last year, display revenue totaled $2.4 billion, or 31%.

In other categories, classifieds lost market share, coming in at $1.7 billion, or 17% of total revenue, compared to last year's 20% ($1.6 billion). Email held relatively steady at 2% ($200 million). Referrals and lead generation increased to $799 million, accounting for 8%, from last year's $592 million (7%).