Forrester Research predicts that the total market opportunity for U.S. online advertising and marketing could reach $26 billion within the next five years. For 2005, Forrester is predicting $14.7 billion in overall spend, which means that online advertising will almost double by 2010.

It looks like this is a zero-sum game, as traditional advertisers increasingly deal with the loss of advertising dollars to the online upstarts: "Almost half of marketers plan to decrease spending in traditional advertising channels like magazines, direct mail, and newspapers to fund an increase in online ad spending in 2005." In addition, marketers are likely to experiment with new forms of online media as they look for the perfect mix: "64% of respondents are interested in advertising on blogs, 57% through RSS and 52% on mobile devices, including phones and PDAs."