Heights; Or rather, terrible pain caused by falling from a high height...
Needles; I've always been paranoid of needles, maybe it's because I watch too much Higurashi.
Spiders; I just hate them. I can't explain why. I guess it's because I'm a girl, and being terribly afraid of spiders is a typical female thing. I really do hate them though.
Eternity; I know it's probably a pretty weird thing, but I'm afraid of the concept of eternity- like being in an afterlife for a never ending time, or being non-existant for all of eternity... Yeah, that kinda scares me when I think about it.