MSM, or Methylsulfonylmethane, is a sulphur containing compound. There is some evidence that MSM, in conjuntion with other supplements, helps a bit with osteoarthritis pain and swelling. There is also some early research that indicates it may help reduce joint degeneration.
MSM supplements also plays a role in your hair, skin and nails. Wrinkles may be reduced, hair is fuller and nails are shinier.