I'm in the stage of planning new CMS. Before I used WordPress and other open source CMS for my clients, but I always had to write new modules and even mess with the code in order to do certain things. Which as you understand is not the best thing to do. So I finally decided to make my own CMS to work with, the way I need.

But before I start it, I would like to think it trough carefully to ensure that I won't need to rewrite it ground up, just because I forgot to include some feature into architecture or did it wrong.

I would like to hear your thoughs and the most important I would like you to suggest me some articles or books on that subject, especially on architecture of such systems. I googled a few good books, but that is not enough.

The way I'm planning to do it: PHP5, completely OOP, modules architecture. You make a page and add any modules you need there, but modules are not global, but local to a page so you can make two pages with the same module, but content will be different if you set different "content ID" for these two entities. But it can be set the same, so two pages has the same content of the modules put there. Also I plan to support online storage web service (like amazon S3) for images and files, so I would like to hear your thoughs on it too.

Also I have not yet decided how to store language data. I don't want to use DB for that, but I haven't decided yet. Also I think I will support other DB with global DB class and separate DB wrappers for MySQL and other databases.

And, well, I would appreciate any other information you can provide for that subject.