According to the Advertising Forecast from Kagan Research, the Internet, interactive TV and satellite radio will be the major drivers of growth for U.S. ad revenues.
Via ClickZ:
The Internet remains the strongest-gaining sector in advertising, averaging 57 percent growth per year over the past 10 years. In 2005, the channel increased by 24 percent. New channels experiencing the most growth last year include satellite radio (235 percent) and interactive TV (116 percent).
Revenues from more traditional channels experienced lower rates of increase. In 2005, total ad revenue, including traditional and interactive channels, grew by 3.9 percent to reach $240 billion. Ad revenues are expected to reach $400 billion by 2015
Even traditional advertising media is positioning itself to take advantage of it.
Traditional sectors like TV have made moves to hold onto ad dollars; many traditional media are creating properties on the Internet.