Have you looked at admin_main_center.tpl?
There are already smarty variables created such as:
{$members} = total number of members
{$total} = total number of stories submitted
{$published} = number of stories published
{$queued} = number of stories in the queue
{$votes} = total combined votes of all stories
{$comments} = total number of comments made on the site
So for example lets say you want to show the total number of published stories on the home page.
Open index.php and add
Code:
$published = $db->get_var('SELECT count(*) from ' . table_links . ' where link_status = "published";');
$main_smarty->assign('published', $published);
Then open index_center.tpl and add something like
Code:
{$published} total published stories