James O'Keefe is the conservative extremist activist who is known for posing as an ACORN pimp. He was supported by Glenn Beck and other FauxNews anchors. He was arrested for attempting to tamper with Senator Mary Landrieu's office phone line and to try to ruin her life
Brooklyn & California: No wrongdoing by ACORN
In September 2009, fellow conservative extremist activist Hannah Giles and James O'Keefe published questionable edited hidden-camera videos in which Giles posed as a prostitute and O'Keefe claimed to be her PIMP. They claimed this was to show ACORN employeees providing advice to them on how to avoid detection by the authorities while they told them of plans to engage in tax evasion, human smuggling and prostitution.
However on March 1, 2010, the district attorney for Brooklyn concluded that there was no criminal wrongdoing by the ACORN staff in the Brooklyn ACORN office. An investigation report by California Attorney General, Jerry Brown released in 2010 found the videos from Los Angeles, San Diego, and San Bernardino to be "severely edited" and did not find evidence of criminal conduct on the part of ACORN employees. O'Keefe and Giles were just trying to destroy a good organization like ACORN which helped people register to vote, including minorities. 
Phone Tampering & Arrest
In January 2010, O'Keefe and three editors of conservative college publications were arrested by the FBI at the office of Senator Mary Landrieu on suspicion of trying to tamper with the senator's phones and charged with a felony. In May 2010, O'Keefe pled guilty and was sentenced to three years probation, 100 hours of community service and was fined $1,500. As dangerous as he is, he should have gotten more, especially that he also conspired with another conservative extremist, Lila Rose, who is as wacky as he is and they teamed up to try to sabotage Planned Parenthood with sting videos, falsely accusing the abortion providing organization of being dishonest and racist.
Attack on NPR
In March 2011, he and others posed as Muslims trying to donate money to NPR. They recorded Ron Schiller saying that The Tea Party is racist and xenophobic, which we all know is true. But, the nutjobs are turning this into a victory as they want to destroy NPR.
Attack on Planned Parenthood
Recent attack video, was released in time to defeat federal funding for research into breast cancer. The video, produced by an O'keefe associate, and intended to imply that reimbursement for shipping costs was sale-for-profit of fetal tissue, was also intended to aid Presidential candidate Senator Rand Paul in the stripping of federal funding from planned parenthood. Speaker of the House John Boehner used the video as an excuse to convene a house investigation. It remains to be seen if false quotations and citations widely distributed on the WWW and attributed to Planned Parenthood advocate Margaret Sanger are also an O'Keefe production.