It has been a summer of staged outrage--a.k.a., astroturf.

As President Obama promoted his health care agenda this summer, mobs of angry Americans greeted him at town hall meetings. They had been orchestrated by lobbyists and political interest groups.

Astroturf groups are grass-roots citizen movements run by powerful corporate and political interests.

"It is optics--making things look as if there is more controversy than there is," said Lisa Graves, executive director of PR Watch, a non-profit that monitors front groups.

But a look at their funding sources and origins reveal shady associations to corporations and lobbying groups. This is a look at some of the most successful astroturfers influencing discourse in America.