"End of Month Report"
I think it'd be great to have the system send an "End of Month Report" to each client with stats like:
Average workouts per week.
Personal Bests summary
Nutritional summary with average calories, carbs, fat, protein.
Most "online fitness options" do something like this as a way to give clients a feeling of accomplishment at months end. This would be a great way for us to show how we are helping clients get stronger and healthier.