[calorie]

Shot in the dark, untested, and all that with vBulletin 4.1.0 Patch Level 2...

Say you want active users in the navbar template when you are on the forum.php page. Try adding a plugin to the forumhome_complete hook with this code:

vB_Template::preRegister('navbar', array('activeusers' => $activeusers));

Then use the following in the navbar template wherever you want it to appear:

<div>
	<ol class="commalist">
		{vb:raw activeusers}
	</ol>
</div>

If it works, you can do the same type of thing as above except for the forumdisplay.php page change the hook to forumdisplay_complete and use the following instead (because $navbar is set earlier in forumdisplay.php than forum.php so create it again):

vB_Template::preRegister('navbar', array('activeusers' => $activeusers));
$navbar = render_navbar_template($navbits);

And for the the showthread.php page, the hook would be showthread_complete with the same code as with the forumdisplay.php page.

Whatever vB kicks out to $activeusers on those various pages should (unless this is all baked) be what you get in the navbar save for tweaks.