...At Democratic think tank NDN, Simon Rosenberg estimates the campaigns will set aside less than 2 percent of their ad budget for the Internet.

SIMON ROSENBERG, PRESIDENT, NDN: It's too low, it should be higher, but politics tends to lag behind the commercial advertising trends.

GERSH: Control is a concern. No campaign wants to see the candidate's banner ad pop up next to something obscene. Even so, this campaign has proven the power of online social networks to raise voter interest and money.

ROSENBERG: It's exciting because what it's doing, more than anything else, is allowing average people to play a meaningful role in the life of their democracy. That's a healthy thing.