This site shows a category ribbon along the top. The category ribbon has been manually created in a block, but the relevant css is present in the theme.
The code in the block is of the form:
<div id="cat-1" class="category">
<a href="#">Text that goes under the category title.</a></p></div>
Just place the above html in a block, set the input format to something that allows div elements and css styling (I used the full html input format after turning off the html corrector).
A full width region takes 5 of the categories to fill - in the above sample just replace "cat-1" with an appropriately numbered id (cat-2, cat-3...).
If anyone can think of a good way to automate this, have some gui for it, I am all ears.
The css for the category ribbon does not work perfectly on IE6 - the current behaviour is for the text and background colours to stay the same as before.