Sleep and meditation
I have.  The hypnagogic/hypnaponic state is known for the interesting and even intense phenomena that can arise.  Here's my most vivid experience:


  I woke up one morning, paralyzed.  This happened before (sleep paralysis), and I knew it was a symptom of the hypnagogic/hypnaponic state. Well, I had recently read a book on out-of-body experiences (OBE), and it stated that I should simply will myself to lift out of my body.  So I did.
  
  I then felt a buzzing sensation up and down my body that grew to a
  fevered pitch.  It was INTENSE.  Then I felt myself lifting out of my
  body, with a static-electricity-like sensation at every point I exited. Then I
  saw the ceiling coming closer through CLOSED EYELIDS.
  
  I was terrified, so terrified I wanted back in.  I ended up
  snapping back in, and literally shivered myself to sleep.
  
  Then I woke up again, and heard strange music.  I never heard this song
  before, but the voice sounded like Sinead O'Connor's.  I then felt the
  buzzing again, like it was a spontaneous OBE.  I fought it hard, and
  it stopped.


The above was very vivid, more vivid than my waking experiences.  I chalk it up to the hallucinations (or lucid dreams) possible from this state.