We recently found the Breathing Zone app, which does an approximation of what Resperate does, and Mr. C has successfully used it on the (very packed) train on the way into work without people thinking he is crazy. He tells me it's good, and he would recommend it for travelling although it certainly won't be replacing our Resperate machine as it doesn't have all of the features or flexibility.
A good way to cancel out the effect of your morning coffee then? :-)
