On his blog, Jeroen Keppens writes about his love of modular design philosophies, and how one can do modular based design, using Zend Framework and Zend_Tool

I admit. I am a sucker for modules. I like my code nicely seperated in manageable blocks, that I can reuse whenever I want. Needless to say, I’m a big fan of the modules in Zend Framework. It isn’t always very easy to set it up though. I had to look long and hard for answers on several questions and I noticed a lot of people had the same ones. So, I decided to make an article on creating a modular application in Zend Framework.

Through the process he describes in detail, he steps you through creating a modular application, tying in a library, module specific layouts, and working with models and view helpers.