There are so many to choose from! Here are a couple ideas, please add your own comments.
What's new in Revit 9 - This would be an examination of the new tools, how we'll use them. Plus we could look and see if they addressed our wish list items.
Rendering in Revit - We could share techniques and examples, since there's not much written info out there on this topic. And incidentally there are a number of awesome rendering artists in Ontario who are using Revit.
Stay tuned, we'll keep adding to this...