"The lie about the documents from Niger (which turned out to have been forged) are a big part of the case the Bush administration used to convince Congress to pass legislation allowing Bush to attack Iraq."

As with the above, another case of poorly handled information on the part of the intelligence community, although that might be being awfully unfair to some members of the US intelligence services, as reports exist that some analysists were unhappy about the way this information burst into the public domain. To make this a lie, it would have to be proved that the CIA (or who ever) deliberately started rumours about Iraqi approaches to the Government of Niger regarding sales of Uranium Cake years ago. That Saddam Hussein has been interested in a nuclear weapons programme cannot be disputed, this interest has been well documented over the past 25 years. You would then have to prove that members of the current American Administration knew that these documents were forgeries prior to presenting them to the public. I do not think such proof exists on either count.

Here is an article that was originally published in the Baltimore Sun on April 4, 2003. It addresses concerns that the intelligence gathering agencies have about the way the Bush administration is using/misusing information about Iraq:

"Some former intelligence officers and historians say they are seeing a worrisome pattern of Vietnam-style politicization of intelligence, with pressure to play up the threat from Hussein's weapons of mass destruction and to minimize the potential for Iraqi resistance and the threat the war poses to regional stability.

They note complaints from current CIA analysts as well as glimpses of deeply flawed evidence used by the administration to make the case for war, including documents purporting to show Iraq's attempts to buy uranium from Niger for nuclear weapons. The documents turned out to be forgeries, as CIA analysts had warned before the alleged uranium quest was used by President Bush and Secretary of State Colin L. Powell to illustrate the looming danger from Iraq".

"Patrick G. Eddington, a former CIA analyst, said current agency officers have contacted him and other agency veterans in recent weeks with complaints of political influence.

"We've heard from multiple sources inside the agency about the pressure to conform," says Eddington, who resigned from the agency in 1996 after accusing superiors of covering up evidence of possible causes of gulf war syndrome. "They say they feel pressure to shape estimates to support the administration's positions - or at least not contradict the administration's positions.""

Some Worry U.S. May Bend Facts for Policy:
Analysts pressured to spin reports to support White House position, veterans say

Here's an article from Veteran Intelligence Professionals for Sanity: Cooking Intelligence for War