Hopefully others will contribute too.... 

The module so far to date is fantastic and has just about everything you could want. In the interest of community spirit here are a few suggestions;

1. Like categories, it would be great to link to to the social api in DNN. If you had the option of linking an instance of a module to a Role Group (like the social groups module) where you could link events to Groups (much like you do with categories). You would then be able to filter group events from the drop down list. This would be fantastic, especially since creating social groups is so easy, linking events would come naturally.

2. It would be great to have the option of setting the days of the week to show in the month view. I would love to be able to remove Saturday and Sunday from some projects.

3. Including sub calendars is great. Extending this out a little, it would be great to have the ability to refresh the calendar automatically via jquery (without having to use meta refresh or hack some javascript in there). 

That's it for now!