Tell the media. 
When Richard Nixon abused power, Congress held a serious, bi-partisan investigation that resulted in articles of impeachment. Strong evidence suggests that George Bush and Dick Cheney launched an illegal war and lied to Congress, spied on Americans without court approval, leaked classified information, produced phony news reports, imprisoned without charge and tortured, targeted civilians and used illegal weapons. Ask your Congress Member to cosponsor House Resolution 635 for an investigation.
Contact info for House Judiciary Committee Democrats .
H.Res.635 would create a select committee to investigate the Administration's intent to go to war before congressional authorization, manipulation of pre-war intelligence, encouraging and countenancing torture, and retaliating against critics, and to make recommendations regarding grounds for possible impeachment. Full text PDF 
The AfterDowningStreet.org coalition, an alliance of over 100 grassroots organizations, has launched a new campaign called CensureBush.org in order to support new legislation introduced by Congressman John Conyers that would censure President Bush and Vice President Cheney and create a select committee to investigate the Administration's possible crimes and make recommendations regarding grounds for impeachment .
H.Res.636 and H.Res.637 would censure, respectively, Bush and Cheney for failing to respond to requests for information concerning allegations that they and others in the Administration misled Congress and the American people regarding the decision to go to war in Iraq, misstated and manipulated intelligence information regarding the justification for the war, countenanced torture and cruel, inhuman, and degrading treatment of persons in Iraq, and permitted inappropriate retaliation against critics of the Administration, for failing to adequately account for certain misstatements they made regarding the war, and – in the case of President Bush – for failing to comply with Executive Order 12958.
H Res 636 PDF 
H Res 637 PDF 
The House Judiciary Committee Democratic staff has just released an extensive report titled "The Constitution in Crisis: The Downing Street Minutes and Deception, Manipulation, Torture, Retribution, and Cover-ups in the Iraq War." It is available here. 
HERE IS UPDATED VERSION, AUGUST 2006:
The After Downing Street / Censure Bush Coalition has organized over 60 town hall forums around the country on January 7th and plans to make these new developments in Congress a focus of many of those events:
Tim Carpenter, Director of Progressive Democrats of America (PDA), and Co-Founder of After Downing Street, said: "Progressive Democrats of America is proud to be working with Congressman Conyers for the passage of H.RES.635, H.RES.636, and H.RES.637. We thank Congressman Conyers for his leadership and are excited to be working with the grassroots to mobilize and organize a broad base coalition that will demand action from Congress to investigate the lies of the Bush administration and their conduct related to the war in Iraq."
Bob Fertik, President of ImpeachPAC.org and Co-Founder of After Downing Street, said: "The publication of 'The Constitution in Crisis' marks a turning point in American history. It's long past time for Congress to hold George Bush and Dick Cheney fully accountable for the crimes they committed before and during the disastrous Iraq War. I am certain that a serious investigation of these crimes will lead to the impeachment and removal of both Bush and Cheney."
Attorney John Bonifaz, Co-Founder of After Downing Street and 2006 Massachusetts candidate for Secretary of State, said: "The people of this country are waking up to the severity of the lies, crimes, and abuses of power committed by this president and his administration. Now is the time to return to the rule of law and to hold those who have defied the Constitution accountable for their actions."
Bill Moyer, Executive Director of the Backbone Campaign, adds: "'Culture of Corruption' does not do justice to the Bush Administration's systematic undermining of the checks and balances of this republic. Add spying on Americans to the already long list of crimes in the Conyers report. The 'I word' (impeachment) has become the elephant in the room. Congressman Conyers, the Backbone Campaign is honored to support your efforts."
PRESS RELEASE FROM CONGRESSMAN CONYERS
Congressman John Conyers, Jr.
Michigan, 14th District
Ranking Member, U.S. House Judiciary Committee
Dean, Congressional Black Caucus
Contact: Dena Graziano 202-226-6888
CONYERS RELEASES REPORT ON MISCONDUCT OF BUSH ADMINISTRATION CONCERNING IRAQ WAR
Calls for Censure of President Bush and Vice President Cheney
WASHINGTON, D.C. - Representative John Conyers, Jr., Ranking Member of the House Judiciary Committee, released the following statement regarding today's release of a staff report entitled "The Constitution in Crisis: The Downing Street Minutes and Deception, Manipulation, Torture, Retributions and Cover-ups in the Iraq War." The Report is my best effort to examine all of the charges of misconduct by the Bush Administration concerning the Iraq War.
Conyers Report: http://www.house.gov/judiciary_democrats/iraqrept.html 
"In brief, we have found that there is substantial evidence the President, the Vice-President and other high ranking members of the Bush Administration misled Congress and the American people regarding the decision to go to war in Iraq; misstated and manipulated intelligence information regarding the justification for such war; countenanced torture and cruel, inhuman and degrading treatment in Iraq; and permitted inappropriate retaliation against critics of their Administration. There is at least a prima facie case that these actions that federal laws have been violated - from false statements to Congress to retaliating against Administration critics.
In response to the Report, I have already taken several initial steps. First, I have introduced a resolution (H. Res. 635) creating a Select Committee with subpoena authority to investigate the misconduct of the Bush Administration with regard to the Iraq war and report on possible impeachable offenses. In addition, I have introduced Resolutions regarding both President Bush (H. Res. 636) and Vice-President Cheney (H. Res. 637) proposing that they be censured by Congress based on indisputable evidence of unaccounted for misstatements and abuse of power in the public record. There are a number of additional recommendations in the Report that I expect to be taking up in the coming weeks and months.
The Report rejects the frequent contention by the Bush Administration that there pre-war conduct has been reviewed and they have been exonerated. No entity has ever considered whether the Administration misled Americans about the decision to go to War, and the Senate Intelligence Committee has not yet conducted a review of pre-war intelligence information, while the Silberman-Robb report specifically cautioned, that intelligence manipulation "was not part of our inquiry." There has also not been any independent inquiry concerning torture and other legal violations in Iraq; nor has there been an independent review of the pattern of cover-ups and political retribution by the Bush Administration against its critics, other than the very narrow and still ongoing inquiry of Special Counsel Fitzgerald."
Link to Congressman Conyers' site:
Censure Bush graphic at top contributed by Shakespeare's Sister .
1998 Congressional Research Service report on Censure: what it is, how it works: PDF .
1998 Congressional Research Service report on Impeachment: what it is, how it works: PDF .