Here is a video of Team Fortress 2, with voice chat, a karaoke mode and Celine Dion's 'My Heart Will Go On'. The singing is terrible, but I can't stop watching because it is so hilarious.
Hmmm... what would it take to do that in World of Warcraft? I'd need a small add-on that takes karaoke data and outputs it using /rw, then trigger a sound file on Teamspeak at the same time.... Sounds like a great little project for learning Lua, heh heh heh *twiddles moustache*. Anyone know of open karaoke data formats?