Code:
-----[ OPEN ]-------------------
blocks/block-Login.php
-----[ FIND ]--------------------
?>
-----[ INSERT ABOVE ]--------
if (is_user($user)) {
$content = "<center>[ <a href=\"modules.php?name=Your_Account&op=logout\">"._LOGOUT."</a> ]</center>";
}
Go to Blocks administration, set Login block visibility to "All Visitors"
Tha's it! Works on v7.6patched2.7, but should work on almost everything