The first, and most obvious second chance is the one afforded to Shoeless Joe Jackson. Getting a chance to play baseball again, after being banned, and after being dead, is more of a third chance. Near the end of the first chapter, Joe explains how much he loved/loves baseball. This melancholy and longing for what he missed also shows how much he appreciates this second chance to play.
I'd play for the Devil's own team just for the touch of a baseball. Hell, I'd play in the dark if I had to.
At the end of the first chapter, Joe is so grateful that he asks Ray if he is in heaven.
Near the end of the second chapter, Salinger expresses his regret that he didn't take more chances. He says this shortly before he decides to take a risk, thus a second chance for more passion in his life. That risk is to go with Ray to Iowa.
"I wish I had your passion for baseball," Salinger says. "However misdirected it may be, it is still a passion. If I had my life to live over again, I'd take more chances. I'd want more passion in my life. Less fear and more passion, more risk. Even if you fail, you've still taken a risk."
Moonlight Graham has no real regrets; he's happy with how his life turned out. But after his dialogue with Ray - about baseball and wishes - he begins to think. When asked if he had a wish, he replies:
I'd have liked the chance to stare down a pitcher. Stare him down, and then wink just as he goes into the wind-up; make him wonder if I know something he doesn't, if he should change the pitch in mid-delivery. Yes, that's what I wish for, Ray Kinsella: the chance to squint my eyes when the sky is so blue it hurts to look at it, and to feel the tingle that runs up your arms when you connect dead-on. The chance to run the bases, stretch a double into a triple and flop face-first into third base, wrapping my arm around the bag.
Two of the best quotes that I have heard in reference to second chances are both truthful and applicable to anyone's life:
"Life isn't forever, so take the first chance, don't wait for the second one! Because sometimes, there aren't second chances."
"Everybody deserves second chances, but not for the same mistakes."