Online advertising grossed $21.2 billion in 2007, beating cable ($20.9 billion), radio ($19.8 billion) and broadcast television ($19.2 billion), according to a report commissioned by the Interactive Advertising Bureau. Of that, 41 percent went to search advertising — which means, for the most part, Google. The total represents a 26 percent increase over last year. What's potentially problematic?

Consumer ads, for such which includes retail, automotive and entertainment sectors, accounted for 55 percent of that — and that's the market most threatened by an economic downturn. Maybe time to break into the billboard business? (Photo by Danny O'Brien)