That's a great suggestion. Our current infrastructure for the mood tracker doesn't support this, but we'll look into ways of how we can add the ability to track multiple moods per day. We'll let you know when it's available.
I would add my support to this, too. I can be horribly depressed and totally manic and absolutely apathetic all in a single day, so I end up having to go with whatever mood lasted longest, or some kind of average, or whatever I best remember.
Thanks for the suggestion. We just wanted to let you know that the Mood Tracker now accepts multiple moods per day. Just select a mood and then click Specify Time. To add more moods, click "Add another".
To see public Mood Trackers, including those that have multiple moods per day, check out the Mood Tracker Gallery: http://www.medhelp.org/user_trackers/gallery/mood