/**
        *
        * Custom single template for certain category
        * @author: hamer121
        */
        add_filter('single_template', 'check_for_category_single_template');
        function check_for_category_single_template( $t ){
            foreach( (array) get_the_category() as $cat ){
                if ( file_exists(TEMPLATEPATH . "/single-category-{$cat->slug}.php") ) return TEMPLATEPATH . "/single-category-{$cat->slug}.php";
                if($cat->parent){
                    $cat = get_the_category_by_ID( $cat->parent );
                    if ( file_exists(TEMPLATEPATH . "/single-category-{$cat->slug}.php") ) return TEMPLATEPATH . "/single-category-{$cat->slug}.php";
                }
            }
            return $t;
        }