A few months ago whilst working behind the scopes we heard the TCAS warning on the background of a pilot's readback. For some reason we thought that it would be pretty cool to have that "TRAFFIC TRAFFIC etc" sound as a ringtone for the mobile. A search didn't reveal any source for this until I bumped into this website a couple of days ago where you can download a number of sounds. The coolest being the GPWS off-course, that whoop whoop sound does it for me.
http://www.aviationringtones.com/