Nothing?
There have been plenty of opportunities for the world to act to end the reign of Saddam. CIA helped Saddam gain power in his coup, the world supported him when he invaded Iran by suppling him with WMDs and the US refused to support the rebellion against Saddam after the Gulf war.
Maybe we should just let the inspectors destroy what WMDs there are left (because that's their mission right? not to overthrow Saddam right?) and then just bug the hell out. The sanctions have caused a lot of suffering, weakning the internal opposition and strenghted Saddams regime. Why are you in favor of destroying the inspections regime with an illegitemate mission to overthrow the Iraqi regime? Don't you care about the threat of WMDs?
There are plenty of dictators out there oppressing "their" people. Why is necessary to overthrow Saddam now, at great human cost ("Hiroshima effect" and all)?
An iraqi opposition intellectual living in Sweden, who supports the war, says that he believes Saddam can murder one million americans - you be the judge if that is a reasonable price for installing an american military governor in the Middle East.
This war will speed up the race to gain WMD capability in the third world - it's the only guarante against being invaded by the US. Is it worth it, to tear the world asunder just to get one man?