Many people on the Wordpress.org support forum are asking how to do this.
Here is the simple solution I came across. It will allow you to display the title of a child category without displaying the parent category.
Put this code in your template:
PLAIN TEXT
PHP:

<?php

$category = get_the_category();

echo $category[1]->cat_name;

?>

(Adapted from this code at Wordpress.org.)
The [1] [...]

After much searching followed by some searching and then some more searching I have finally struck upon a method for showing recent PHPBB3 posts in Wordpress. There are a lot of methods out there and little bits of code but they are not all packaged up neatly in plugin form. Thanks to Nick [...]