[Joe Gardner]

Yes, I have done this on my forum, example: http://www.bikeforums.net/showthread.php?t=38748

In the postbit template, ad this at the very bottom:

<if condition="$post[postcount] == 1">
<if condition="$bbuserinfo[usergroupid] == 1">
<-- ADVERTISING CODE -->
<br>
</if>
</if>

This is shown to guests only, once a member registers, I have moved the ad down the page, right above the quick reply. If my registered members donate, they go ad-free.

The next change i will make is to ad the code to the TOP of the postbit template, and change the postcount line to "2". This way, the ad will be shown in the same place, but only if the thread has more then one post.