GSnap - With GSnap you can get an auto-tune effect.
Linux Show Player - Sound player designed for stage productions
Celemony Melodyne - Celemony Melodyne is the perfect quick and easy tool for all your tuning needs.
QLab - QLab, Live show control for Mac OS X.
CrispyTuner - Fully featured vocal tuning suite.
Trigger Audio and Video Playback - Audio and video cue player for broadcast and live performance.