Heh, running, skipping, who cares.
Jumping rope is also a SPECTACULAR workout for your calves and axial skeleton. I know people whose exercise plan consisted solely of jumping rope. It can be intense as you make it.
The best way to run in place is to hold your hands out in front of you about solar-plexus level, and then as you run, touch your knees up to your hands (move them up even higher than this if you can). It does look somewhat ridiculuous, but its the best way to get a good workout running in place (and I know this doesn't apply to you, but it's a great warmup for an actual run). You also want to do it fairly quickly, to keep the intensity up.