You've probably read about the scientific studies proving that praying or being prayed for is beneficial to one's health. According to skeptic Michael Shermer,
these studies are deeply flawed, suffering from faults such as failure to eliminate other factors (such as socioeconomic status, lifestyle differences, and people in poor health being less likely to attend church). There's also the small matter of one of the authors of one study being a fraudster. (via FmH)