To use it, copy tomsnow_v2.js to a directory on your web-server, and add the following code to the head of any pages on which you would like snow, changing the domain as appropriate:

<script type="text/javascript" src="http://www.yourdomain.com/path/tomsnow_v2.js"></script>
<script type="text/javascript">
function init () {
  snow();
}
window.onload=init;
</script>

To view or change the options, see the source code of tomsnow_v2.js itself. To see the snow in action and for more of an explanation, visit http://www.aurochs.org/tomsnow/