Today brings an updated release of TuneQuiz. From the change log:

1.2 -- Added the ability to select music source for playback
Added the ability to rescan music sources
Added the ability to start a new game
TuneQuiz now fully quits when the close window button is pressed
Redesigned preference pane as a drawer
Minor code speedups
Redesigned icon

This also includes the ability to use shared music sources from other iTunes users on your network. To use the shared source, be sure to connect to it in iTunes prior to scanning sources. Enjoy!