Cancer-afflicted teens often have a hard time sticking to their meds. So Pam Omidyar — a tech enthusiast with a background in immunology and wife of eBay founder Pierre — came up with a spoonful of new sugar: video games. Two years ago, HopeLab, Omidyar's not-for-profit, released Re-Mission, a shooter game in which players destroy cancer cells. But it wasn't until this past summer that clinical evidence was published showing that the game actually works. According to a paper in the journal Pediatrics, patients who played for at least an hour a week were more likely to follow their drug regimen. HopeLab president and CEO Pat Christen says the video-game therapy can be applied to other diseases and conditions. Right now, she says, they're working on technology to help vanquish childhood obesity.