They have become a place to store treasure, and therefore prized possessions. If you are organized enough, you could start this tradition when your kid is two. Write down a memory from each year of life your child has lived on the inside cover - a little love note. I like to think my kids will cherish these things one day, and forgive me for all the mistakes I am making along the way. Sometimes we don't know where we come from, or where we are headed unless we can see the roads we have traveled.
Sketch books make good journals.
While your child is very young, she will need assistance writing her life from people who know how. Sometimes the candle makes little smokes - smokee, smokee, smokee. Take the journal to grandma's house. These entries will be appreciated later on. This method is an easy way of noting down life's travels, and makes rereading the journal a lot more fun.