The scene of attack at the end of the book is a great place to look for courage. Jem in this scene has the courage to fight the attacker and protect his sister - he only stops when his arm breaks. Boo Radley has the courage to step in and fight for the children as well, ultimately saving them from Bob Ewell.
The character of Boo Radley exemplifies courage. He is alienated by the town, either ignored or feared. He grew up with an abusive and controlling father. Despite these things, he shows a strong sensitive and compassionate side. He has the strength to reach out to the children, leaving them gifts and protecting them when needed. He has the courage to face a whole room of people when he carries Scout home from the attack. A quiet courage, maybe, but courage still.
One example you might not have considered is the courage of Mayella Ewell. She has the strength to face the town in the courthouse and submit to Atticus' cross-examination. She has the courage to stick to her story when Atticus begins to show the holes in it. It may not be a wise move, but her actions in court are courageous. She is, after all, doing what she has to do in order to protect herself.
The first one to come to mind is Mrs. Lafayette Dubose in Ch. 11. Atticus makes Jem read to her for what first appears to be punishment for Jem losing his cool and thrashing her flowers. However, toward the end of the chapter, the reader realizes that Atticus wanted to show Jem how courageous Mrs. Dubose was, for she was dying. Her doctor had prescribed morphine for her pain. As a result, she had become addicted to morphine. However, she did want to leave this life being addicted to anything. This is the real reason Atticus had Jem read to her. Not only did it offer her a distraction as she tried to break the addiction, but he did it because he also wanted to show Jem was true courage was. Atticus tells him after she has died, "She was the bravest person I ever knew" (112).
Another example of courage is surely Atticus's acceptance of the Tom Robinson trial. Look at how many people think he should not really do anything to help him. However, Atticus fights his hardest for Tom. Aunt Alexandra notes this in chapter 24 when she tells Miss Maudie, "They're [the citizens of Maybomb] perfectly willing to let him do what they're too afraid to do themselves . . ." (256). When no one else steps up to defend an innocent man accused of rape and facing lynching or an unfair trial, Atticus steps up - despite the risks to his family - and does what he believes is right. That is true courage.