William Bennett - book of virtues
William Bennett - The Moral Compass
Bill Gothard's Character Sketches books - tough reads, but good to read together. especially if your son likes animals.
I haven't read the Trailblazer series of christian biographies for kids, but I'm intrigued.
Building Christian Character - post from my blog with good character books
Great post from my homeschooling friend Christy Reeder about character-building books
Some classic books that are likely to have great character/leadership/life lessons:
Where the red fern grows
Wrinkle in time
Island of the blue dolphins
My side of the mountain
Chronicles of narnia
Swiss family Robinson
The black stallion
Treasures of the snow
Little house on the prairie
I look forward to hearing your favorite character-building books!