Chords scales are very useful for improvisation as for accompaniment. In a
simple way, insted of playing a note, a chord can be played with the same
upper voice than the note. Then, whole phrases can be build around chords
scales : many great pianists have intensively used this kind of
technique, such as Wynton Kelly or Bill Evans.
A simple chord scale can be constructed in C major, starting from a four
voicings C Maj7 chord. If our first score is CGBE, the next one will be
constructed raising each voice of a degree in C major : DACF, EBDG, and so on, as shown on this picture :
This may seem rather trivial and useless as these chords are very well
known and completely tonal ones. But if you consider less used chords like
these ones, things sound differently, especially on the guitar :
Each of these chords may be the starting point of a chord scale, built in
the same way than before, by raising each voice of a degree in the
tonality (D Major, or E Dorian for this example which is a E minor scale
with a C Sharp). Check out these ones :
These chords sound rather unusual (for me 
), especially on the
guitar because of the half tone interval in the middle of the chord, which
offers many ways of playing these chords in an arpeggiated way :
