The speaking in a deep unnatural voice was something I heard a girl did while she was possessed. Along with having some sort of strange stone. (I think she was into witchcraft-y stuff, but I don't remember.) Anyway, they knew that this stone, for whatever reason, was evil. But no matter what she did, she couldn't get rid of it or destroy it. So then she was in a church or something, and the pastor and a bunch of people prayed over her, and they tapped the stone with a hammer and it shattered into a bunch of pieces, as if it were exploding. I don't remember the details to that story, but it was something along those lines. The demon also spoke, and said it's name was "Dark Jaguar" or some strange thing and said other stuff, too.
Also, here's another one that I really like. My church was having a women's prayer meeting, and one woman said she saw a hooded person among the people praying. She said that the person was wearing black, and looked like he didn't belong. He then walked through the wall, and left the room.
The woman told the youth pastor what had happened, and he asked what time this had happened. When she said 3:00 he was suprised, because he remembered being completely full of rage for absolutely no reason and that when he had looked at the clock it was 3:00.
Just... ineteresting.
I've heard a lot of things from people that have witnessed demon possesion, or have been serious practicers of witchcraft.