Internet ad spending will account for 7.0 percent of global ad spend in 2008, according to a forecast update from ZenithOptimedia, which increased its outlook from April, when it had projected a 6.5 percent share (and 6.0 percent in December) for internet ad spend, reports ClickZ. The "pace of development in Internet advertising" was the factor cited for the most recent upgrade.

Online advertising spend is expected to reach $23.9 billion this year, $28.6 billion in 2007 and $32.5 billion in 2008 - or an increase of 75 percent from the $18.5 billion in 2005, according to ZenithOptimedia.

ZenithOptimedia estimates that financial services advertisers were the biggest online spenders in 2005, accounting for $1.6 billion in online ad spend, writes MediaPost; telecommunications companies were second with $1.5 billion, followed by retailers ($1.3 billion) and car companies ($700 million).