Jumping rope is something I do almost everyday. After injuries to both knees, I skip instead of run (occassionally I will run some hills or find a grassy area to jog). I will skip in rounds or keep moving for 15 to 20 minutes at a time. I mix it in, double unders, squat jumps, high knees, etc. and move around the gym (adding some footwork in). Here's a great clip of JT Van getting down with the rope showing how boxers use them.