Create a true clock

I want there to be an actual clock on my webpage. I figured out the basic php to get the local time for the reader and or th server time. but what i really need is a way for this to keep updating (maybe AJAX or something?) with out reloading the page. the final product would a small digital clock on the side of the page.

I am making a small plugin out of this just so the code is easily maintainable

inside the plugin is the following

function nattime() {
$now = localtime( );
print “$now[2]:$now[1]:$now[0]
“;
}

and in my page
<div class=”blox”>

The Time is Currently
<?php nattime() ?>
</div>

any help to make the time update more frequently then a full page refresh would be helpful