One thing I didn't know if my son was coordinated enough to do was jump rope. He's got great motor skills but I wasn't sure how he'd respond to it. I know it would be helpful espeically when he loves the trampoline. (I unfortunately need to make a new cover that goes around the springs especially with the baby being mobile.) Anyhow, I found some cheap plastic jump ropes at target for about $3. (In my opinion they work better than the fabric rope ones or leather ones and lighter than the beaded ones.) Anyhow, my son took to jump roping very easily and so he's been jumping in our living room. (It was snowing outside.) We kept track of how many times he got over the rope and he enjoyed it a lot. He can jump over right now 2-3 times in a row.
Another idea that works well if a jump rope won't work is sitting on an exercise ball and bouncing on it. I have used both the regular and the stability and I strongly suggest the stability if you don't want it rolling around all that much. My kids of all ages have loved the ability to be on the ball bouncing up and down and rolling around on the floor.