I found this enlightning and interesting article about cracking joints on http://www.eatmoveimprove.com/, it answered a lot of questions I was doing myself, I really recommend you to read it if you also have this kind of problem:
Since I was a child my knuckles cracked and clicked, even unintentionally! I can crock almost everything in my body: fingers, wrists, elbows, neck, knees, ankles...my pelvis bones also!!!
My parents always told me it was dangerous and would grow up to cause arthritis, other people says it's harmless.
The main problem is that often I feel discomfort if I don't crack my joints, like if I couldn't move well untill I "free" and loosen up them and now that I'm a professional dancer this started to bother me a lot!
Every time I crack my legs and feet joints I feel like I'm guilty and I'm condemning myself to be doomed, now I know I could have lax articular capsules and must strenghten them up more ( I dislocated my left shoulder 2 times already ... ).
So the answer is: exercises, exercises and more exercises!