Harmonics
Harmonics are produced on the flute in a similar way as on brass instruments: by fingering one note and manipulating the embouchure to produce different pitches according to the harmonic series. For instance, by fingering a low C, the following pitches are possible [demonstration, with graphic?]. Composers use harmonics in a variety of ways; one of my favorites is in the "Sea Nocturne" variation in George Crumb's Vox Balaenae, or Voice of the Whale. Here, several harmonics are alternated with regular fingerings in rapid succession to create a "shimmering" effect.