Teresa Amabile and Steve Kramer on the benefits of keeping a work diary:

Experiments by psychologist James Pennebaker and others have revealed that writing about traumatic or stressful events in one’s life results in stronger immune function and physical health, better adjustment to college, a greater sense of well-being, and an ability to find employment more quickly after being laid off.

Not bad. I hope regular blogging counts too. (After all, what is a blog but a public online journal?)