Karaoke is a great way to entice the inhibited into singing and unite the group through the medium of popular song.
Dr. Olivia Yinger-Swedberg has typed song lyrics into a presentation software program on her iPad, which was controlled using her phone. University guitar students played the music and helped children sing the words.
http://jennieyuen.blogspot.com/2012/01/singfit-music-therapy-app.html Singfit was designed by a music therapist. A monthly subscription buys you a catalogue of songs with the ability to adjust key, cue, vocals, and more. I have not tried the app, but it seems like the most helpful approach to a beginning singer.
http://www.karaokeparty.com/ This site has a great selection with a majority of free songs categorized by genre that you can sing with or without vocals. Use is dependent on internet access, but you can open songs up in independent tabs or windows and bring them with you.
James E. Riley, MT-BC