This thread is so long there's no way i can look through the whole thing! But, I'm going to say that my Secret compartment book I made for my boyfriend last valentine's day was a huge
I found an old book on greek plays at a used book store, and followed some of the tutorial pages that you can find using the search. I put some felt on the bottom to make it more classy, and then posted a picture of his favorite philosopher, Jon Locke, in the front (he has a philosophy degree). This is a cool gift for siblings, or even someone you don't know well, just cause it's so rad.
Here are some pics: