S-adenosyl-L-methionine (SAMe)

The Dec/Jan Real Simple mentions this amino acid (one that naturally occurs in the body) as a good supplment for joint pain. It does seem to be effective, not only for this but for depression as well, but the jury is still out on whether it should be taken the way one takes glucosamine, for example. It’s also extremely expensive. Here are some links:
http://www.stoneclinic.com/sam_e.htm
http://www.biomedcentral.com/1471-2474/5/6
http://www.biomedcentral.com/1523-3812/5/460/abstract