Those of you who mentioned strong aversions to smacking/crunching/eating noises, take a look at this: http://en.wikipedia.org/wiki/Misophonia
I find such things mildly annoying, unless I'm in a really bad mood--then, I could strangle the person before they take another bite or slurp.
(J/k...maybe.)
Still don't swim. I nearly drowned when I was 6, and never really got over it.
Don't drive either, but I'm more worried about causing an accident and hurting others than hurting myself...I know, weird. Trying to get over that one. I have a very bad time multi-tasking, so keeping track of everything that driving requires is really difficult--I find myself starting to panic just getting behind the wheel.
Going on the "loud noises" thing: smoke detectors with horns/buzzers. The one we had when I was growing up would often go off for no reason at all (steam from the bathroom near it, burnt toast, you get the idea). I dreaded walking under it (it was on the ceiling), or even seeing one in its box at a store. Where I'm living now, they just beep, and they don't malfunction, so I'm largely over that one.
I'd say that a lot are sensory-related. Those of you who mentioned insects and snakes--not that unusual in the general population, actually.
_________________
The existence of the leader who is wise
is barely known to those he leads.
He acts without unnecessary speech,
so that the people say,
'It happened of its own accord.' -Tao Te Ching, Verse 17