Here's one example of her wonderful voice:
And this is one as for being the conscience of her time:
Performed on the March on Washington as well (right, it's where Martin Luther King held his famous speech). Too bad there's no proper video of it :/
BTW, Joan Baez and Bob Dylan were lovers once. If she wouldn't have pulled him onto stage back then, who knows, he might not be as popular now. And might not got the Nobel Prize either

Here's a beautiful song she dedicated to him about ten years after they split up:
If I only was one or two years older, would you marry me, Joan?
