Show categories in the sidebar of Outlook? Is it possible to show Categories in the Navigation Pane (left sidebar) of Outlook 2011? If so, how?
You could create a Smart Folder for each of your categories to accomplish this.  In the search bar, search for "category:yourcategoryname" and hit enter.  The Search tab in the Ribbon will appear.  There, you can select "Save", which will save your search as a Smart Folder.