I was asked by my Aunt a couple of weeks ago to partake in this little project that she does with her friends every once in a while. It consists of finding a book, usually a used book that catches your eye in some way and altering part of it. You can change it in any way you like (cut/paste/draw/paint) whatever you can think of really. The reason i say to only alter part of the book is because after changing it in some way you mail it to the next person.
It works best when you have several people so when you send your book you receive another one in return already partly altered. Do this several times until your original book comes back to you full circle. Snail mail baby!