Very simple solution, no hacks or widgets.
Add this code to wherever you want it (but customize the child_of=3 to your parent category)
<?php wp_list_cats(‘sort_column=id&optioncount=0&use_desc_for_title=0&child_of=3’); ?>
Heres an explanation of what it does:
“<?php wp_list_cats(‘sort_column=id” = list categories
“&optioncount=0” = don’t include the count of articles
“&use_desc_for_title=0” = sort by title descending
“&child_of=3′); ?>” = all categories under the parent category 3
Hope this help you all
Renegade