There are 103 active Dead Ghost locations including the "Vex 5" ghost which is a Playstation exclusive. Now, some of us have a higher dead ghost count than 103, but that's our little secret ;-)

I don't know the amount in game right now, but there is a website that helps you track them. I think if you google "destiny ghost tracker" you will find it. Also, it's been awhile but if I remember correctly, Datto had a really good tutorial for finding all the ghosts.