I fractured a rib almost 2 years ago (~from a bad cough/cold). Huge knot the size of half a tennis ball. I was training for my first marathon 8 weeks away, and was determined to keep training for it. We had an athletic trainer at the local university who taped my right rib cage (helped stabilize the area/muscles), and I just ran easy every day for about 5 weeks (~100-110 mpw). We also did e-stim and ice a couple of times a week. I agree-- coughing, laughing, sneezing, breathing hard, sleeping on that side were painful, but very easy running was fine. I actually felt better after each run (endorphins?).
I happen to in the field of bone research (I was finishing my Master's in grad school at the time), so I had the inside scoop on enhancing bone recovery. You want to eat lots of meat (IGF-1, growth factor), fruit and vegetables (potassium citrate, buffers acid load in diet), and sleep a lot (GH release in your sleep). All of this combined with the low-level mechanical stimulus of running (~rib is non-weight bearing) will enhance bone recovery. I was pain free after 3 weeks (the norm is 6-8 weeks!). I was able to start doing some harder workout stuff after 5 weeks. I ran the marathon with no problems, although I wasn't quite as sharp as I could have been.
Whatever you do, do NOT take ibuprofen or any prescription pain relievers. They will slow the healing process and reduce the amount of callous formation. Calcium/Vit. D supplements will have no impact on enhancing recovery, but they will certainly be important for forming new bone mineral. Bisphosphonates won't enhance recovery either, but over the long term they will improve BMD by slowing bone resorption/removal (however, there is concern they reduce bone quality, which means greater bone fragility/more microfractures within the bone).