Someone turned me on to a very simple solution that allows you display photos that are linked to cells by using the comments feature within excel.
In order to make this work effectively you'll need to go into the "Tools" menu and select "Options". On the "View" tab make sure that the "Comment indicator only" radio button is selected and then press OK.
Start by selecting the cell and add a Comment (with no text). After adding a Cell Comment, right click in the cell and choose Edit comment. Now double click the dotted outline of the Comment where the size handles are, and then click the "Colors and Lines" page tab. From this page click the drop arrow from the "Color" box and then "Fill Effects" and finally "Picture" then "Select Picture".