Of course it goes without saying that the best examples for men/boys are found in the sunnah of the Prophet, salla Allah alayhi wa sallam.
Here are some contemporary, secular resources.
Manners for Boys: "Gentlemen" - An Endangered Species? 10 Simple Steps to Raising a New Generation of Gentlemen!
Teach Your Sons to be Gentlemen
Teaching My Son to Be a Man
Ladies and Gentlemen - Courtesies (PDF)
E How - How to Raise a Gentleman