Not to steal Lawrence's thunder or anything, but the Saturn hardware was one of the most widely licensed game platforms in Japan next to the 3DO. JVC, Samsung, and Hitachi stuck Saturn chips and capabilities into all manner of devices. Note that the ability to suppress the vocal frequencies of music playback is present in all Saturn BIOS versions, so technically the Saturn already supports limited karaoke functions. All you have to do is add a microphone port a la the Wondermega and you've got your karaoke machine ready to go.
-KKC, who meant to get more use out of his Saturn this weekend...