The Outlook Journal can be configured to track time spent working on
documents -- such as Visio diagrams, Excel spreadsheets, Word
documents. It records when the document was opened and when closed. I
have found it somewhat useful -- in a limited way -- in helping me
record my work activity. I can check the journal to see when I opened a
document to start working on it.

Other than that, I have not found much use for it. Interested to hear
what others say.