Heya
This is how I highlight a question with a selected answer in a custom theme:
function a_count($post){
if (@$post['answers_raw'] > 0){
$style='has-posts';
}
if (@$post['answer_selected']){
$style='has-selected';
}
$this->output_split(@$post['answers'], 'qa-a-count', 'SPAN', 'SPAN',@$style,
@$post['answer_selected'] ? 'qa-a-count-selected' : null);
}
That way you can take a class such as .has-selected and set it to something like: .has-selected {border: 6px solid yellow !important;}.
Or give it the star background image aswell. This way you can add more pressure on users to flag a good answer.
I'd like to allow users to manage flagged answers on there post also, this would shift more administratiion over to the user while empowering them with greater functions, you could always freeze answers if the user becomes inactive for x amount of time.