Breaking an axis - is it ever a good idea?
I used to be a "don't break the axis" purist. I like to think that I have learned better. Nowadays, whenever I know that zero does not make sense for the data I am visualizing, I don't hesitate to break the axis.

A little example: I recently started recording my weight (in kg) and reducing my calorie intake. Here is the time series. Does anyone think that the plot on the right is more informative? It isn't. Because zero is not a possible weight for a healthy 39 year old male.