I was thinking about the books that I have read in my teacher education preparation program and in my spare time. These books have definitely made me a great differentiator:
How to Differentiate Instruction in Mixed-Ability Classrooms : The first edition of this book was required by my teacher education program. It is a great primer for differentiation, and it has many great ideas on how to differentiate content, process, and product.
Differentiating Instruction With Menus for the Inclusive Classroom : This book is one of my absolute favorites. I saw this randomly on Amazon and decided to buy it. It's a whole series, so although the link is to the middle school science one, chances are there's one specific to your classroom. This is just the one that I own and that I have read. In this book you will find multiple types of menus, ideas for activities to put in your menus, and ideas on grading menus. My favorite happens to be the baseball themed menu. I actually tried that one in my classroom, and it worked wonderfully!
Layered Curriculum : I am currently reading this one, and I absolutely love it! This is a lesser known gem that takes the idea of menus and amplifies it. Students get to choose the activities that they do (including whether or not they participate in lectures, or even recorded lectures). They also get to choose their grade basically, because the activities are tiered into an A, B, and C level. It's pretty awesome! I can't wait try a layered mini unit.