I bought Journal Bliss by Violette on journaling a few years ago and love how she shows creative ways to fill your journal- doodles, collage, image transfer, backgrounds, etc. Very inspiring and creative!
There are also some excerpts from the book on the Creativity Portal website,which has a lot of ideas to get your creative juices flowing.
In a Google search, I also found images from the book if you want to see how it's illustrated. Maybe you will be inspired to start your own journal (if you're not already).