pictures as characters in a Tk text box?

[Jay]

This may be really obscure, but I had a dream about programming
something like this, so don't blame me.  Is it possible to take a small
image or icon and display it as a character in a Tk text box?  Think
how Thunderbird displays text smilies as actual smiley icons.  Or how
in AIM as you type a smiley, it replaces it with the picture.  Does
anyone know how to display these specifically in a Tk text box?  Thanks.