On the librivox.org forums we have a thread where people can post general thank-you notes for the whole team (there’s a different thread for thank-you notes to individual readers).
This recent note warms my heart:
I teach in a maximum security prison. Most of my students had never read a book before. I have been using librivox audio readings with them to help them read the book as a class. It has made a tremendous difference for these men. Every time we finish a book they are anxious to start the next one. Thank you to all those who have put forth the time and energy to do the readings. You have made a great impact on these men’s lives.