It's interesting, but as I thought about what workout I could do, I started to ponder the differences between strength training and conditioning. In a nutshell, the goal of strength training is building muscle mass -both for good looks and to build strength/power. The goal of conditioning is building endurance. That being said, the approaches taken to each is different as well.
For example, when strength training the goal is ading reps and resistance. So after a few weeks of 20 pushups, start doing 30. Or after benchpressing 3x8 reps of 100lbs, go to 110. While with conditioning, it is more of a time game - as in run for 20 minutes or do as many crunches as possible in 3 minutes.
With conditioning training, the goal obviously is to watch that number steadily climb as time progresses. The idea is to get you performing at your peak over a specific period of time - and I think that is what I am going to do.
My time situation easily lends to this, as I will only have a few minutes for calesthenics each day, but hopefully they will get me into better shape and provide me with good results.