I'm obsessed with the elliptical trainer...

http://www.advancedfitness.com/news/elliptical.htm wrote:Weight bearing exercises like running, hiking and aerobics benefits the body in ways that non-weight bearing exercises like rowing and cycling cannot. Weight resistant workouts builds bone density and burns calories more efficiently.

For individuals trying to burn calories and trim down, the weight-bearing arm/leg exercise optimizes energy expenditure during self-selected exercise of moderate intensity in overweight subjects. In recent studies it was concluded that energy expenditure among overweight subjects was higher on the elliptical machine than a treadmill, or leg cycles with and without upper body motion. For overweight individuals who are initiating a regular exercise program to decrease excess body fat, they will find that elliptical treadmills optimize energy expenditure.