Journal to the Self: Twenty-Two Paths to Personal Growth - Open the Door to Self-Understanding bu Writing, Reading, and Creating a Journal of Your Life | 
pickOne of my favorite books on journaling; perhaps because of the shared belief of the journal as confidante and form of self-therapy. For those who have never kept a journal and find themselves lost as to what exactly to write about (because "just write about yourself" is so vague, so HUGE...), this is a great starting point.