The Utah PHP Users Group has the second object-oriented related article in the series posted over on their site today - Thinking object-oriented (Part 2 of 5).
This is the second of five articles written on object-oriented programming. These articles were originally written for jacwright.com. This article was going to be entitled Conceptulizing Systems, but was changed to Thinking Object-Oriented as this title better describes the content of the article. I hope these are of benefit to you.
They talk about different approaches: "Top Down" thinking, "Bottom Up" thinking, modeling it after the real world, and, finally, true object-oriented thinking. They give examples of these methods, but no code to give an example of what they might look like...