Thanks Skippy for the explanation of the_IDfunction, and for putting me on the right path.
Your fix didnt work right away but after some tinkering with it, I made it work:
The solution is
<?php $side = $wp_query->post->ID;
wp_list_pages("child_of=$side".'&'.'title_li= ');?>
It could probably be more elegant, but it works.
