Nothing so far. What keeps me going is the potential in the long run and the SEO aspect; such as backlinks. They are more valuable than the earnings.
Experienced Hubbers say that they earn a lot. Some as many as $XXX, which is a considerably good amount as things are autopilot. But you might want to put up as many hubs as possible to reach there.
But, stay here. You'll earn in the long run as you go along, which is a also a long-term goal of mine.
Good luck! :) (for both of us..LOL)