Tiger Woods... the first great Black golfer. No question there.
The Williams Sisters (not twins) - Good for business? I think things were going better for Woman's Tennis back when Chrissy Evertt was queen.
Great Black QB? - Doug Williams? didn't exactly light people's fires. Slash, er Cordell? Nope. Michael Vic... maybe if he stays healthy. Trouble with your Tiger analogy is that he is the greatest of all time. Any QB, black or white to dominate football like Tiger does golf would be richer than god. In other words, his race is secondary.