Amazing! What a great site.
I am 53 years old, still playing soccer and Tennis, and just about every one of my joints have cracked since I was a boy.
These days I dont crack my fingers as much as I used to, but I need to crack my spine every morning and several times during the day. Its never painful, always satisfying, and is followed by a period of comfort and well being. My hips, Knees, and ankles also pop regularly, Ankles are easy and crack whenever I flex them. I do have a bad back occasionally, but I am certain this was caused by a lifetime of bad posture and poor lifting, and the spinal cracking is what resolves my pain as opposed to causing it.
I visited a chiropractor when I was in my 20's and he brought students to observe as he popped every vertibre from my a*s to the top of my neck just by using gentle massage followed by spinal rotation. He descibed me as a "popper"!!
I have no arthritis and am in general good health dispite a lifetime of being told "its not good" and "I will regret it when I'm older".
I cannot offer any words of wisdom or knowledge on the subject. I was told by a doctor that the popping sound was due to the release of gas from the cartilidge, but I do not believe this is always the case.