Salon has an op-ed Impeach Bush | Salon.com by Garrison Keillor. I do not know much about Keillor, but he has only touched the tip of the iceberg.
There are plenty of other reasons. This guy lied about the intelligence leading to the Iraq war. Then he used chemical weapons (white phospherous). Apparently for americans white phospherous is not reason enough to impeach (“inappropriate act’ was though!).
I am glad that at last the american media is waking up.