Here's a tool I've been using with my CSS Professional Development classes. It's taken from the International Center for Leadership in Education. You can find a more colorful version on their site (http://www.leadered.com/rrr.html).

An expansive collection of articles on integrating curriculum from The Small Schools Project.  It is broken into 3 sections: Why Integrate Curriculum, How To Integrate Curriculum, and What Integration Looks Like.  This is a large document, so the Table of Contents is helpful.