There were a series of genocides in Saddam Hussein's Iraq, including the use of chemical weapons against Kurdish civilians in 1988 and an estimated 300,000 Shia Muslims murdered in the southern third of the country after the 1991 Persian Gulf War.
Short of invasion, there are really only two ways to stop genocide, and neither of them are guaranteed effective. One is a no fly zone, which the US enforced from 1991 - 2003. This prevents air attacks and chemical weapons attacks, but does little to effectively stop ground forces. Two is to arm and equip rebels on the ground to fight their own battles, similar to what was done in Afghanistan in the 1980s, and in a more limited way, what is being done in Libya now.
I agree with the above poster though in saying that putting "boots on the ground" is the only real way to have controlled what went on there, and that was politically and practically impossible in both the instances I mentioned earlier.