[fernando]

You may want to check this mod out. It works with categories of any depth, although it will only list the first level of sub-categories for the current category.

Open customer/categories.tpl

replace:

{if $config.General.root_categories eq "Y"}
{section name=cat_num loop=$categories}
<FONT class="CategoriesList">{$categories[cat_num].category}</FONT>

{/section}

With...

{if $config.General.root_categories eq "Y"}
{section name=cat_num loop=$categories}
<FONT class="CategoriesList">{$categories[cat_num].category}</FONT>

{* Added by Fernando. Show first level of subcategories *}
{if $current_category ne "" }
  {section name=subcat loop=$allcategories}
{assign var=topmostcat value=$allcategories[subcat].categoryid_path|regex_replace:"/\/.*/":""}
{assign var=current_category_top value=$current_category.categoryid_path|regex_replace:"/\/.*/":""}
    {if $current_category_top eq $topmostcat and $categories[cat_num].categoryid eq $topmostcat and $allcategories[subcat].parentid eq $topmostcat and $allcategories[subcat].categoryid ne $current_category_top}
      {$allcategories[subcat].category|truncate:20:"...":true}

    {/if}
  {/section}
{/if}
{* End added by Fernando *}

{/section}

Cheers,