Thanks for the link Steve, I went from there to the http://www.eatmoveimprove.com/2009/1...-dysfunctions/
article which was great as well.
I'm not sure whether my knee is cracking or clicking, I guess it's more cracking since it's a "compound sound" not a single noise (if that makes any sense...).
Anyway the noise is on the front, maybe slightly to the right. I've been getting quite a bit of fish oil daily for the last few months so I doubt diet is an issue.
I need to push the knee forward besides my toes to get the cracking, if I squat down and up with the shin vertical it does not happen.