The moonless nights are also refered to as the New Moon. The new or dark moon resembles the end as well as the beginning. These three nights bring peace, silence and balance. If you are in the process of wanting to start something new, such as a diet, sending out resumes, a job interview or sowing and planting should do so during this moon phase.
Root vegetables are best harvested during this time, they are most beneficial in nutrients and energy.
The dark moon phase is also best for reversing spells (always be sure there is one there to begin with).