Peter Pronovost, MD, a Johns Hopkins University researcher made famous by his checklist study, has been named to Time magazine's 100 list. Pronovost, 43, began investigating hospital-acquired infections at Johns Hopkins' hospital in 2001 and concluded that arming physicians with a chart reminding them of each step in routine procedures drastically reduces the medical errors that lead to such infections. Pronovost says the checklist protocol could be rolled out nationwide within two years for less than $3 million.