KaraFun - KaraFun is the best online karaoke. Over 35,000 karaoke songs, with studio quality, at home or on the go. Regular updates. Free demo!
GSnap - With GSnap you can get an auto-tune effect.
Yokee - Karaoke to YouTube videos
Celemony Melodyne - Celemony Melodyne is the perfect quick and easy tool for all your tuning needs.
Sing! Karaoke by Smule - Karaoke with your favorite celebrity singers
Antares Auto-Tune Pro - Auto-Tune Pro by Antares is the latest and enhanced version of Auto-Tune that offers Auto Mode to correct pitch and Graph Mode for step-by-step modifications of time and pitch.