M-x artist-mode

I thought I was past the point of being surprised at the number and
variety of features lurking in emacs, but I was wrong. href="http://www.lysator.liu.se/~tab/artist/">Artist is a
mouse-driven ascii-art drawing program. It has all the features you'd
expect from a rudimentary bitmap editor (rectangles, ellipses, flood
fill, spray paint, etc), with all the user-friendliness of emacs (Want
to draw an ellipse? Type C-c C-a e). You can href="http://burnallgifs.org">burn all your gifs and replace them
with ascii art in <pre> blocks. Unfortunately it
doesn't work in xemacs.