The coefficient of friction of skin would depend on the moisture level, I think. For instance, if my fingers are dry, they slide easily across across each other. If they are moistened, they stick more to each other.
The coefficient of friction for rubber varies spending on what rubber (it's combination) you are referring to and is it static or sliding friction. It can be as high as 1.16 (coefficient of static friction) for rubber in combination with itself while it can be as low as 0.25 (coefficient of sliding friction) for rubber mixed with Wet Asphalt.
As far as Human skin is concerned it is again subjective to conditions for instance the location of the skin and whether it is wet or dry. The average coefficient of friction is 0.46 +/- 0.15 and the palm of the hand has the highest coefficient of friction 0.62 +/- 0.22 when tested with 5 materials namely aluminium, nylon, silicone, cotton sock, and Pelite.