The iPhone's missing ringtone
The Apple iPhone TV ad uses a ringtone which is not included on the iPhone. After much searching I eventually found it via this thread on Mac Rumors. The ringtone is loud and urgent sounding, and much more attention-grabbing than the iPhone's built in ringtones.

Already converted to .m4r format (for ringtones), this file will install itself into the iTunes ringtones folder, allowing you to sync it with your iPhone.