The Book of Sirach is another that is in Catholic Bibles but not in Protestant ones. Though the introduction to my commentary has a lot of theories about it and information, it basically reminds me of Proverbs.
My dad and I have discussed this part, as for some reason we find it amusing:
Sir 3:12-13 O son, help your father in his old age, and do not grieve him as long as he lives; even if he is lacking in understanding, show forbearance; in all your strength do not despise him.
I think that means that even if he goes crazy, I'm still supposed to be nice to him!