Hi,
I was just looking for a way to display the number of the top categorys (depth=1).
Maybe this is not exectly what you are looking for, but i think you might customise it for your needs.
I used a db query to get my results:
$numcats = $wpdb->get_var("SELECT COUNT(*) FROM $wpdb->term_taxonomy WHERE parent=0
AND taxonomy = 'category';");
echo $numcats;
It displays exectly what I needed (the number of the topcategories) but if you use an other query string you might get your results.