My friend Neil uses a Roland Discover 5 as a karaoke machine - it comes with a load of songs and lyrics in it (like Toto's 'Africa' and 'Like a Virgin'), and has various vocal effects and auto-tune things.
Now Mikey has found something far better. It's the Yamaha Disklavier Mark IV, a grand piano with loads of electronics built into it. Those screens (and the little PDA) are wireless controllers, you can control the piano from anywhere in the house, selecting which PianoSoft® title you're going to play.
As the brochure says: "Turn any gathering into a karaoke party, with the lyrics displayed with customizable backgrounds on the tablet remote. The Disklavier Mark IV’s karaoke function lets users hear their voices complete with digital effects like reverberation and vocal harmony… your virtual backup singers" It also has a built-in 80gb music library, making it the most expensive MP3 player ever made. Best of all, it's got carbon fibre strings. I'm not sure why, but it has.