If your family has one or more toddlers, chances are that Eric Carle's Brown Bear, Brown Bear, What do you See? gets a bit of mileage at your house. The book Building Character from the Start: 201 Activities to foster creativity, literacy and play in K-3 has a great idea for making a homemade companion book. (By the way, I'll be giving away a copy of Building Character from the Start later this week; so stay tuned!)
I just used pictures we already happened to have of family members in costumes (I especially enjoyed including the picture of my husband from Chick fil a dress up like a cow day), but it might be extra fun to have a dress-up photo shoot especially for the making of the book. I glued my pictures onto a blank board book for a little added durability, but you could just use this format if you don't have any blank books on hand.