Just a couple thoughts that I've seen pop up from our users.
it would be nice if on the event sign-up window, it displayed who is coordinating the event.
We let our members use the calendar system to plan non-dkp runs as well, but of course do to guild drama, some people don't necessarily want to run non-dkp events when set up by specific users.
Also, I think it would be cool to have a full view of the event calendar that would could go to so that they didn't have to mouse over every date to see what's happening that day/week/month
could just be same calendar but larger with each event listed maybe with start times and then the user could do a mouse over to get the rest of the details. it would go go into the content section like news / forums and maybe either have a link from the mini calendar or "Menu" pain where the Admin nav is.