Since this seems to be a recurring topic for discussion, I'd like to make a sticky thread in this forum to describe the various applications out there for sound cue playback. Please post a short description of a cue playback program if you are familiar with it, as well as requirements (platform, interfaces,
etc) so that folks unfamiliar with the options available can decide what program(s) best fits their needs.
I'll start:
QLab (Mac Only)
http://www.figure53.com/
Free; Advanced licenses available (>8 channel playback; MIDI; Video)
QLab is a Mac-based cue playback system that can play back audio files, video files, MIDI cues, and many other things. It features the ability to use up to 8 channels of output in the free version, as well as advanced cueing features. There is a large user base for QLab, and an active mailing list dedicated to user support.