jQuery Impromptu provides a nice way of implementing a pop-up feature.
Flag of course flags a node.

<?php
  // Load necessary to avoid error
  module_load_include('pages.inc','privatemsg');

  // Adds javascript to header
  jquery_impromptu_add();

  // Gets rid of whitespaces that break javascript code
  // drupal_get_form retrieves the privatemsg form
  // $uid is the author of the node
  // $title is the title of the node
  $form = str_replace("\r", '', str_replace("\n", '', drupal_get_form('privatemsg_new', $uid, $title)));

  // javascript that runs jquery_impromptu on flag event
  print '<script language="javascript">';
  print "
  $(document).bind('flagGlobalAfterLinkUpdate', function(event, data) {
    if(data.flagStatus == 'flagged'){
      $.prompt('$form');
    }
  });
  ";
  print '</script>';

  // Necessary because previous module_load_include changes title
  drupal_set_title(check_plain($node->title));
?>

For more information on how you can customize the privatemsg form, look here http://drupal.org/node/624528

<?php
function chkuri($link){
//$link is the website which i am checking
// If file_get_contents failed to retrieve
// the page, it's not up
  if(!file_get_contents($link)){
    return 'I\'m sorry, but the Ampache server is down. :(';
// It is up
  }else{
    return 'It\'s up! <a href="'.$link.'">Click here to go!</a>';
  }
}
print '<h2>'.chkuri('http://martinez.homelinux.org/ampache').'</h2>';
?>