Below are some ideas / reference material for soloing over a C minor (min7, min9) chord. Wherever "pentatonic" is indicated, I am refering to a "minor pentatonic".

C Dorian mode (Bb major scale)
Eb maj7 arpeggio - includes 9th
Am7b5 arpeggio - produces minor 6th sound

-== Triad Superimposition ==-

Eb major triad
F major triad
Bb major triad

-== Pentatonics ==->

C pentatonic
D pentatonic
G pentatonic

.....and for more "outside" ideas....