I have this theory about deja vu (From French, already seen), although its probably deja vécu (already lived). Anyway, from my own experience and intuition about it, what I think happens is this: when you are asleep and in the dream state, time doesn't exist, the normal rules of awake don't apply. You therefore can experience possible futures and you don't usually remember these experiences, but occasionally you do. So the possible future you experienced becomes the actual future and when the moment arrives, and if you are in the right state of awareness, the memory resurfaces and voila! deja vu.
The same probably applies to prophetic dreams but I have found that prophetic dreams aren't as accurate as deja vecu, in that they seem a bit more unreal or symbolic.
I once had a dream that I was upstairs (at my real school at the time) in a dark classroom and that people were applauding me. When I recalled the dream I thought "that's strange, why would I be applauded in a dark classroom?". A few days later I had video class and we were got into small groups and took a video camera and made a movie in about 30mins. When we all were finished the teacher turned off half of the lights, so the room was dark but not pitch black, and then played each groups' film. Probably to give us all encouragement the teacher got everyone to clap after each movie. When ours finished we received our applause and it made an impression on me because I couldn't remember getting applauded before. As I was thinking that, I recalled the dream and put the two together and was amazed.
So from that and other prophetic experiences I know that it is possible to glimpse future events and that is how I came upon my theory of deja vu.
Another interesting experience I had involved following my intuition and a brief prophetic vision.
I was at Crossways Hare Krishna restaurant eating my meal when I suddenly thought about a particular moment in the Seinfeld TV sitcom when Kramer said something funny and I laughed. After lunch I didn't have anywhere to be so I walked to the corner of Collins St and stopped and just waited until I felt where I should go. I turned right and walked down to Elizabeth St and waited again. I headed back from where I'd come. I started walking east down Swanston Walk and thought I'll go to the gardens. When I was near the gardens I needed a pee and I knew there was a toilet down the hill in the gardens, so I headed down. As I walked down I saw a girl who was practising stick twirling where you spin one stick with the other. I thought as I walked past her "if she's still here when I come back I'll say hello". So I go for a pee and start walking back and I see she's still there. So I walk up and say hi and we start talking about her sticks and then she stops and we sit down and chat. She suddenly brings up Seinfeld and tells me about the scene I had laughed at when at Crossways. I told her about that and how I found myself in the gardens and we both were amazed. We kept talking and she told me about her plans to move north and wasn't sure about it. I think I sort of pepped her up with some positive reinforcement and typical Sagittarian optimism and she said she felt much better and it was just what she needed. I remarked maybe that's why I was meant to find her this day. Because I felt a lot better for the experience as well. I can't remember her name, I think she was an Aries or Gemini. I remember seeing her once when I was coming and she was going at Crossways and we just said hi. I wasn't disappointed, I thought it kind of felt right, like a magical moment we shared. God I sound like a hippie...