Today, Gliese 876 e was discovered, hidden in resonance with another planet. E is a Uranus mass planet orbing smack dab in the habitable zone of Gliese 876.
I think this is better than Gliese 581 c and d, because any moons orbiting the planet would get light AND dark, as they are tidally locked to the planet and not the star. This is more promising. And the system could be hiding more planets...