Redirecting on Access Denied Errors

Drupal gives ability to control access to content.

If a user hits some content that gives a 403 error ( access denied ) either because they have not got correct access rights,
or are anonymous it is possible to control what happens next.

This php snippet does just that.

<?php
global $user;
if ($user->uid) {
print $user->name; ?>,
<p>We apologize, but you do not have permission to access this page.</p>
<p>If you feel that you have received this message in error,
please contact us with specific details so that we may review your access to our web site.</p>
<p>Thank You, Technology and Social Action web team</p>
<?php }
else {
$dest = drupal_get_destination();
?><p>The page you requested is available to logged in users only...</p>
<div class="links">» <a href="/user/login?<?php print $dest ?>">login</a> 
or <a href="/user/register?<?php print $dest ?>">register</a> to view this page</div>
<?php } ?>

For more ideas around this see http://drupal.org/node/59861