How about having a colored dot below the day number inside the minicalendar.
That way you can have 4 to 5 category colored dots per day.
I also would like to see the nav section left and right of the month and year display inside the minicalendar.
Thats the way 90% of minicals support navigation from month to month, week to week and so on.
<< May 2013 >>
Best Regards,
Toerti