I recently saw a concert for newly composed contemporary works. One of the stand out pieces for me was for piano and soprano.
Near the end of the piece the soprano sang into the piano while the sustain pedal was held down.
It created a beautiful decaying sound with the sound of a choir.

The Piano Choir library is my attempt to recreate that sound. I sang into a piano with the sustain pedal down, and processed the sounds.
Enjoy. :]