Ive worked in an enviroment where we had to wear Wrist straps ( hand soldering and asssembling PCB boards ) for a short while, and upon dismantling the wrist bad, and sometimes the strap conector contained a resistor ( accessable after being attacked with a soldering iron) from what i was told this has two functions - a slow discharge to protect the components and prevent the static rapidly grounding through your body, and to protect the wearer should there be an errant voltage somewhere flowing the other way.

If you are using one, just remember to:
take it off before you move away from your work area ( some types can whip back like an elastic band)
and take it off before you go out anywhere, as its easy to forget if youve been wearing one for a while, and they look like some sort of tag thing to most people.