My Highest priority for 4.1 is that after sub-calendars are added to  a calendar, that they can be selected from a dropdown in the same way as categories.
I would like each City Department to be able to add their own Calendar events, and have them show on a master calendar.
When all events are listed together the result is nearly unreadable.  The ability to select a few would be great.

Other suggestions:

1. Allow the Dropdowns to be multi-select.
2. The option to display the dropdowns as a checkbox list to the left of the calendar would be a cool option.
3. A month & year selector like this would be cool.
   
4. AJaxifying the Repeat event would make it more straightforward.
   Here is how I arranged the repeat events -

I will send the code this week.