I don't know if mine started out as a what-if. At least subconsciously, I guess. And if nothing else, there's a what-if I can dig out of it later.
So...
Replica's Shadow - What if God really did punish an angel and his descendants 77 times over? (I'd have to dig out an old Bible to be sure it says this somewhere, but I do remember reading something like, "Your children and your children's children will be punished, 77 times over..." or something. Now I'll have to find it. XD)
The Goud Experiment - What if we pulled out of Iraq now, too early? What if the human race was going extinct from the subsequent terrorist attacks and radiation effects? What if some mad scientist had a way to save it? And then of course, I took the route that interested me most--not the scientist's story, but that of one of his experiments. XD
Whisper - What if I took vampyres and made them original and interesting again? What if I, for once, didn't write a love story, be it between vampyres or Michael and a Mary-Sue? (This started off/was inspired by a fanfiction idea back when I was a fan of Michael Jackson, so part of the inspiration was to write something other than a crappy "horror" story Thriller take off or an MJ/Mary-Sue crappy romance XD.) Also, this is one of the original "What if the guys weren't manly-men masculine or tall-dark-handsome types or similar masculine stereotypes?" (For the most part, they're feminine, loving, and emotional, or at the very least feminine/pretty looking)
Dollhouse - What if humans were made out to be living dolls for others? What if someone was collecting these? What kind of psychological effects would all that have, what kind of goals would that give them, what would they be like?
Oriel - These days, it kind of started its final turn of evolution with "What if I changed this from this horrible, elemental-magic-prophesied-one-mary-sue-packed abomination to a gripping, dramatic, meaningful, worth-while story?" Then other things, like "What if Bavol was a hermaphrodite?" (when I made that decision, it was *cue his entire psychological make up and whole-life experience and that thing that explains the previously unexplained* XD), "What if they didn't have any special, magic, elemental powers?", "What if Bavol wasn't uber-special, just...messy?" and so on.
Other what-ifs have been "what if someone knows how they die, and have to try to prevent it?", "what if the answer to the fate-versus-free-will debate is 'both'?", "What if someone went crazy and dreamed about this horrible thing every time he slept, but lost the line between waking and dream world and thought it was happening over and over again...?", and "What if a little boy goes crazy--like his mom--and is forever stuck in a mental state of a 5-ish year old girl?"