Skeptico: Prayer still useless
This is a remarkable review of studies that have claimed to show prayer altered disease outcomes. There had been some poorly done and very small studies that suggested an effect, so it was worth doing some larger studies. The results of the larger studies are all negative.
Prayer to alter the course of disease doesn't work. What effect there was appears to have been a combination of poor study design, data mining for correlations, and perhaps some publication bias (negative studies by persons seeking positive results may not have been published).
I think that theists should find these results reassuring. I would be disturbed if a God were responding to such pleas; it is one thing to live in a world of freedom and suffering, another to live in a world of suffering that God could alleviate -- if He felt like it. For the people He liked.
Pray to God for wisdom, or for help to bear the pains of the world, or for faith or tolerance or greater compassion. Pray not, however, to be spared the pain of our world.