I have been participating in an online swap where everyone makes a page for the other members of the swap group, in the theme chosen by each person for their own personal book (if that makes sense). It's been an interesting experience, and each page needs to be researched so that the theme is executed well. I've learned all about Art Deco, Marie Antoinette, 1950's apothecary methods, Florence Nightingale...etc.
all the participants specified the colours and themes for each page in their House book.
We had to incorporate 'moving parts' on each page too, so that the pages were interactive. I've done this by adding miniature books (on art deco), scrolls that open (marie antoinette), a box of matches and candle (on lady of the lamp), a coin slot (capt.cook), opening doors and pram (on Narnia and Phineas Fogg), and a removable prescription on my apothecary page.
The backs of the pages are also decorated, but I won't post the photos here....
all the participants specified the colours and themes for each page in their House book. 
We had to incorporate 'moving parts' on each page too, so that the pages were interactive. I've done this by adding miniature books (on art deco), scrolls that open (marie antoinette), a box of matches and candle (on lady of the lamp), a coin slot (capt.cook), opening doors and pram (on Narnia and Phineas Fogg), and a removable prescription on my apothecary page. 
The backs of the pages are also decorated, but I won't post the photos here....