aribakker

you should be able to do $cat->category_count to get the count. see the get_categories examples or the category member variables for more information.

e.g.

<?php
  $categories = get_categories();
  foreach ($categories as $cat) {
  echo '<li><a href="'.get_category_link( $cat->cat_ID ).'/"><span>'.$cat->cat_name.' ('. $cat->category_count .')'</span></a></li>';
  }
?>

have you tried using get_category_link?

<?php
  $categories = get_categories();
  foreach ($categories as $cat) {
  echo '<li><a href="'.get_category_link( $cat->cat_ID ).'/"><span>'.$cat->cat_name.'</span></a></li>';
  }
?>