Well, I've had some moments of clairvoyance before, usually from a dream long before the event actually took place, though these are difficult to decipher, and most times don't have anything to do with anything important... Although, I did once do it while fully conscious, although it wasn't an image in my head so much as a huge feeling of dread while waiting(on foot) for a train to finish passing the railroad crossing in front of me.
I was standing a few feet away, maybe about 10 feet from the tracks, when a strange ominous feeling washed over me, and it felt like the train (A very long freight train) was looming over me... It's really hard to describe the feeling, but suffice to say, it scared me a little, and I took more than a few steps back from the train figuring if it really felt that bad to stand that close, some distance wouldn't hurt... A few seconds after I did this, an empty train car (one of those ones with the large metal structure in the middle and no outer shell, and cables crisscrossing the entire length of the car) whipped past me with a loose roughly 20-30 foot cable flailing around on my side of the tracks. Had I not moved, it probably would have cleaved me in half... I haven't had that kind of feeling once since then, but I'll never forget it...
Then of course, there's this:
http://www.youtube.com/watch?v=Ks_UHmaZcSgAnd this:
http://www.youtube.com/watch?v=gIieq0a130cWhich in a way, can sort of explain the possibility of actual Clairvoyance (And not simply jumbled Deja Vu that the brain incorrectly induces from incomplete information), at least theoretically... Essentially, for a brief instant, your brain's molecules might be vibrating at the same frequency as that of another universe, allowing you to catch brief glimpses of it. Time being relative, there's nothing to stop these other universes from being slightly ahead of us, so if what you see happens in the future, it's not out of the question, because that other universe may be ahead of our own. And since our molecules are always vibrating, there's always the chance that as new universes split off from our own, our vibrations might match for brief moments allowing some people to momentarily be in sync with that other universe. So while I may not have had it happen to me due to what ever that feeling was(maybe subconsciously, I picked it up from another universe that was ahead of ours, not sure), in another universe I was killed by that stray train cable that day... I just made myself a little depressed thinking about it like that...
Side note, since we're all technically partially on Mars right now, according to Michio Kaku's second video there... Congratulations! We colonized Mars already and didn't even know it! Take that, NASA!