I was using stars until somebody showed me how to use the browser so that you could exclude from the list books with a certain tag. That way, if you want to only look at unread books, they'll all be there and your read books will be hidden.
I like the asterisk suggestion. I did find that when I had a 'read' tags then items I had tagged as being from Mobile Read would show up too. So the asterisk will solve my problem
