Dear Ryan,
The control that you see inside the Custom Table module on the CMSDesk - Tools section is a UniGrid control which looks at your custom table definition to determine what columns to show.
The Unigrid is a more intelligent version of the ASP.NET GridView control, it's essentially a wrapper around it.
When the UniGrid adds a new column to the GridView control, it can only add one type of column on to the page, which is the type
BoundField, which unfortunately only shows text.
You're only other option to show a list of text with thumbnails would be to create a custom module and write your own implementation.
If you require any further help regarding either topics, please create a new topic to let us now!