In 2010, Google expects the "if you build it, they will come" model to pay off. The company rolled out a new version of its DoubleClick ad exchange in September to open display ad buying to more marketers. "Make it as easy as possible for people to buy display ads, and the pie will grow," says Neal Mohan, vice president of product management at Google in Mountain View, Calif.

The pie Mohan is referring to is the $7.7 billion marketers spent on display ads in the U.S. last year. Even though spending will be up 5% this year, according to marketing research company eMarketer, it's still tiny compared to the $10.5 billion Google-dominated search advertising market. So far, the search engine giant has made only small inroads into Web display, but that's changing. Improved display technology will make ads more appealing to Web users and, therefore, more effective for more marketers.