Update: Sample letter from comments:
Dear Representative __________.
I was disappointed to see that your name was not among the 30 members of the House of representatives that finally have stood up for America by signing H. Res 635 calling for investigation into impeachment of Bush. Surely you concede that it is way past time to do something about the criminal administration that has been ruining the United States for the past 6 years. Waiting for a Democratic takeover of Congress in 2006 in order for us to have a patriotic Congress that fulfills and takes its oversight role seriously instead of actively covering up for the criminal activates of the Bush Administration is insufficient.
Every day, the Bush Administration does additional damage to the United States, the Constitution, our reputation among the nations of the world, and erodes our Constitutionally guaranteed rights. Eliminating the threat within posed by the criminal Bush administration should be the top priority of every member of Congress. The Bush Administration is a threat far worse than Al Qeada.
Please give consideration to supporting measures such as H. Res 635 that could rid us of this scourge ASAP.