so, you have a bunch of mods installed and 90% of them - while they add functionality to your forum - don't add themselves into the list of valid actions in the Who's Online list.
This little trick won't fix ALL of the problems (it's a quick trick, it doesn't drill down into special actions or sub-actions) but it will, at least, display where the user actually IS in your system.
function determineActions($urls, $preferred_prefix = false)
{
global $txt, $user_info, $modSettings, $smcFunc, $context;
global $scripturl;
// Unlisted or unknown action.
else
$data[$k] = $txt['who_unknown'];
// Unlisted or unknown action.
else
$data[$k] = $txt['who_thisaction'] . '<a href="' . $scripturl . '?action=' . $actions['action'] . '">' . $actions['action'] . '</a>';
then add the following text string to modifications.YOURLANGUAGE.txt
$txt['who_thisaction'] = 'Viewing the ';