If I create a few slides and view them on the backend, I see Title, Author and Publish Date. I'd really like to see a thumbnail of the slide's image as well. I think that would be a really cool touch. If you still have my custom_post_type file from my previous thread, how to do add that column is contained, and hopefully, documented well enough for you to modify for your needs. Otherwise Step 4 of this site shows you how.