A little calendar icon to show when something was posted? I seem to recall trying a theme - I forget which; maybe Marinelli? - where each post on the from page had a nice little calnedar icon with the day and month of the pst. 

Is that a module which I can use on other themes?
It's a simple theme modification, probably also easily done via .css. There is not need for a module for this.

Simply edit your themes node.tpl.php page in your theme directory/templates/

Find:

 &lt;?php print $submitted; ?&gt;


Wrap a simple tag round it like so:

      &lt;span class="date_submitted"&gt;&lt;?php print $submitted; ?&gt;&lt;/span&gt;


Write your css:

.date_submitted {
  background: url("../img/icons/calendar_view_month.png") no-repeat scroll left top transparent; 
}


You have to save the calendar image or create your own -> 

You also probably need to do some simple formatting in the css like padding-left (to push the text to the right to stop it overlaying the image) etc ...

If you don't know what I am on about, read up about css3 and drupal themeing and learn some basics.