Who makes it: ElliptiGOHow much: $2,499What it does: Yeah, it's relatively low tech. But the cross between an elliptical trainer and outdoor bike delivers a solid, low-impact cardio workout -- and a readymade conversation piece. The eight-speed version we tested was easy to use and burns 33 percent more calories than a regular bike, with less strain on the knees and other joints. With customers ranging from media mogul Oprah Winfrey to distance runner Meb Keflezighi, who's to argue? On wet or cold days, a stand that is sold separately can turn ElliptiGO back into an indoor trainer.