here an example of use:
// I need to display a single pic of a cheap restaurant in paris
// (provided, needless to say, that I actually have in some gallery
// some picture(s) with all those tags)
$pic_id = nggTags::find_images_id_for_tags_and("cheap, restaurant, paris");
// $pic_id is an array of pctures ID, let me have just the first item
// (and anyway nggSinglePicture need an integer parameter)
$pic_id = $pic_id[0];
// now display that pic
echo nggSinglePicture($pic_id);
