Journaling: worthwhile?

I have read Gretchen's post over at The Happiness Project - about a year or so after I started keeping a one-sentence journal. Well, it wasn't so much a one-sentence-per-day journal as a few bullet points representing the major events of the day.

My last post was in November. I completely ran out of time for personal enterprises, and dropped a number of good habits in favor of sleep and sanity-retention practices. I haven't yet picked it up again - I'm trying to establish some other habits, and as the Zen Habits folk say, one habit at a time. When I think back on the journal, though, I can't remember ever using it as a reference or pouring through it in a huge nostalgia trip. I think I only looked through it once or twice, ever.

So my question is - besides reviewing the events of the day, is a journal really a useful, worthwhile habit to keep? What is its purpose? Do I need it to help remember my life, or are pictures, posts, and friends enough?