Oh this is fun! You know that noise that Motorola's Droids make? "Drooooid" in that cute droid-y voice? Your Mac can make that exact same sound! It feels a little wrong but damn if it isn't satisfying. Here's how:
Just open up terminal.app and type
say -v "Cellos" "droid"
Boom! DROID! Now type a bunch of other stuff and let it serenade you in its sweet robot voice. [Kottke]