Hi,
I really liked the idea of letting the user to choose an icon. It should be allowed for all types of objects, not only events. Maybe depending on the type is what icons you are allowed to select, so that you wouldn't be able to give a document the icon for contacts, since this would create confusion. I'll put it as a feature request, but you can keep developing the idea on this thread if you want. Like, which icons would you like to see?