Some 66 percent of advertisers plan to increase their use of online ad networks this year, according to a new survey of digital media buyers and planners by ad network Collective Media, which also found that 88 percent of the respondents plan to use an ad network - up from 77 percent in 2006, writes MediaPost.

However, the majority said they were frustrated over the number of ad networks and the complexity of the marketplace. Some 62 percent of the media buyers polled said there are too many ad networks, though only 17 percent said all ad networks are pretty much alike.

The survey found that the majority - 80 percent - are using ad networks for direct marketing, while only 6 percent are using them for branding. However, 40 percent are using ad networks for both purposes.

Some 59 percent of agencies/advertisers limit their use of ad networks due to a perceived lack of editorial control, including concerns over the types of ads being used and their position, according to those polled. Moreover, 38 percent of respondents cited audience duplication because of publisher overlap as a major impediment.