The sound from the login screen has always bugged me. It's so loud, it startles me, and it totally stuffs up when I'm trying to "stealthily" log into WoW. I used to just mute my computer for the login so nobody would know I was logging into WoW.
But since patch, there's this little sound thing in the top corner where you can mute that "DOONK" sound! Yay!
Now I can sneak into WoW. Awesome!