I have multiple friends that use the Moto Droid and have the notification sound set as that "Drooooiid" robotic sound. Since I'm the only one with a Nexus One I decided to "represent" and created a quick sound file that is similar to the Droid sound, but simply says "Nexus One".
I'm sure someone could create a better one, but I wanted to share it nonetheless. If someone can create one that sounds better then please share.
EDIT: I added a higher pitched "Nexus One" and I also added a "Nexus" without the "one" at the same low pitch by request.