I am another huge fan of Glucosamine we get this stuff
http://http://www.healthydirect.com/product/0310/d.jsf
and its much cheaper than on the high street.
I used to have pretty knackered knees and this stuff has worked wonders. Pretty much zero aches and pains now. My understanding is that the Glucosamine promotes cartaidge growth but as cartaidge has such a poor blood supply the chondroitin and MSM are needed to act as carriers to get the glucosanine to where it's needed.
One other arthritis cure I know of is apple cider vinegar. If the arthritis is caused by a build up of calcium deposits on the joint (think of gnarled arthritic hands) then this will work wonders. My mother has used this for over 20 years and swears by it. She used to have an arthritic lump on her wrist. Taking the cider vinegar gor rid of it and kep it away but even now if she stops taking it for a couple of weeks then the lump comes back. Recommended dose is 2 teaspoons in warm water 3 times a day. You can put a teaspoon of honey in as well to take the taste away if you want. My mother only takes it twicee a day and finds it still works fine.
The way it works is that apple cider vinegar contains mallic acid (only apple cider vinegar has it so you cant use any other vinegar) the mallic acid dissolves the unwanted calcium deposits from the joints and carries them harmlessly away in the bloodstream. Because the majority of this takes place at the start of treatment it is not unknown for the joint to become more painful than usual for the first couple of weeks.
hope some of this helps
cheers
Stewart