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!
Serum - VST for FL Studio, Ableton Live, and many other VST supported DAWs. Heavily utilized in EDM.
Yokee - Karaoke to YouTube videos
Surge XT - Open-source subtractive-hybrid synthesizer formerly sold commercially as Vember Audio Surge.
Sing! Karaoke by Smule - Karaoke with your favorite celebrity singers
Omnisphere - Piano, pad and synth VST for DAW's.