I'm pretty sure I astrally projected once (really half trying), and the feeling is unlike anything else. I'm thinking Silver Surfer.

And not only that, you can actually feel these cool, buffeting winds as you go (and movement is fast).

Now, it could have been a dream, but my experience jives with what other people have experienced. I almost had it happen a second time, completely awake. My body started getting these weird diagonal waves going across it, which started to affect me physically, and it weirded me out and I broke my relaxation. I felt like I might die (well, if your soul leaves your body, I guess that's death), but I honestly don't know what would have happened had I continued.