Dynamic lists of subpages?

If you copy-and-pasted that directly from your template, it won’t work because the_ID is a function, and would need to be called as such:
<?php wp_list_pages('child_of=' . the_ID() . '&title_li= '); ?>

That won’t work, though, because the_ID() directly outputs the ID to the browser, rather than return it for use in your program:
function the_ID() {
global $id;
echo $id;
}

So, you’ll need to try something like:
$ID = $wp_query->post->ID;
wp_list_pages("child_of=$ID'&title_li= ');

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.

looks like you have a solution, i’ve tried it out and it works well.

i am using another smippet which does the same thing in my sidebar to get subpages to appear:

<?php
global $id;
wp_list_pages('child_of=' . $id . '&title_li=<h2>' . __('In this section') . '</h2>' );
?>

my main problem with both is that NEITHER work on the subpages themselves- meaning they don’t display ‘sibling’ pages; and i want to use this to make a persistent menu.

btw- i’ve seen the folding pages plugin, but i don’t want a collapsing menu.

any simpler options that i’m overlooking?

answering back to the me i was a few hours ago:

you make new file (for example sidebar-page3.php) to be a custom sidebar, calling a specific ID number, like this:

<?php
wp_list_pages('child_of=3&title_li=<h2>' . __('In this section') . '</h2>' );
?>

then include this in a custom template, instead of the regular sidebar:
<?php include ('sidebar-page3.php'); ?>

seems tedious, but it can work.