NASA
Nasa Star Child: What Are the Phases of the Moon?
This page provides basic information about the causes of the phases of the Moon. A good diagram shows the lit portion of the Moon as seen from Earth through one complete Lunar cycle.
NASA
Nasa Star Child: Moonlight Madness
The revolution of the Moon around the Earth causes the Moon to appear to change shape in the sky. These apparently different shapes are called "phases" of the Moon. The Moon passes through a cycle of eight phases which repeats itself...
US Navy
Usno: Virtual Reality Moon Phase Pictures
In addition to providing the current phase of the Moon [within 4 hours] you can find the phase of the moon for any date and time from 1800 to 2199 A.D. Universal, Eastern, Central, Mountain, and Pacific Time Zones will apply to most users.