You have to hear these to believe them. But definitely try before you buy--they're a bit scary.
They're from a site called AviationRingTones.com, and basically, they appear to have been manufactured by an airline pilot or other professional with access to a jumbo jet cockpit and the know-how to activate all sorts of emergency warnings without getting into trouble.
The first one on the list, for example, is called Whoop Whoop Pull Up, and it's the sound you'd hear just before crashing. Other tones are for altitude deviation alerts, engine fire warnings, and the like. Looking for something less scary? There's a tone of a turbo-prop engine igniting. And for the more earthbound, there's a door chime and an engine startup clip from a Porsche.
I heard about AviationRingTones.com from my friend and IDG News Service colleague Stephen Lawson, who sent me a link to it because he knows I've got a private pilot's license. He in turn had heard about from a representative of a site called Phone Sherpa, which makes software that you can use to create and sell ringtones on your Web site.
AviationRingTones.com was on a list of customers that the Phone Sherpa PR manager sent Lawson; others included the 24 Hour Gospel Network and the MySpace site of a Phone Sherpa employee. Maybe everybody will have 15 minutes of fame selling ringtones.