I've had deja vu in dreams more than I have while awake.
I had this one vivid disturbing dream, where I saw a tiny blimp like thing out my window against the blue sky, and it made a noise, and it flew closer and closer to my window...growing the whole time, until it landed on my windowsill as a robot, and then it extended its arm and pointed at my face while I was lying in bed. And the entire time, it felt like it happened before. The noises, the colors, the movement.
....It was freaky dude.... :|