From Baxel Data Systems:
Cue Player is designed to be used by theater-sound people to play sound effects. With the availability of CDs with thousands of effects and the computer's ability to record sounds on its own, it's possible to have all the sounds for the show, including entry and exit background music, resident on a PC. Cue Player can organize those files, associate them with their cue lines, adjust volumes, and show running or remaining cue durations. Cues can be replayed or skipped over--difficult on a tape system. Sounds can be either in WAV or MP3 format.