[duck]

Check out "Smalltalk Best Practice Patterns": http://www.amazon.com/dp/013476904X/

Lots of OO classes use it and Smalltalk is a great language to learn OO with (but even if you don't use it, the general information will be a big help).

[abecedarius]

That's an excellent book, and relevant, but I wouldn't say it directly answers the question: it's more about coding-in-the-small than object orientation. (Those subjects can shade into each other, it's true.)