We've seen many Siri protocol hacks that have innovated and pushed the concept of voice control further beyond what Apple currently allows the software to do. But not even we could envision that robotic voice making for a pretty sweet rapper.
Created by Robert Boehnke for Music Hack Day 2011 in London, Siri is now capable of spitting some lyrics to Notorious B.I.G's Hypnotize, and we haven't stopped laughing yet. If this was in from the start, we would probably have used the service much more than the first months of ownership, as you classify it a gimmick. Check out the video below: