I've done something similar with the "deleted post" handler and have also tried an alternative 'no text' Icon. Have a look at my newly installed experimental boards:
<A HREF="http://www.amdragon.com/cgi-bin/w3t/postlist.pl?Cat=&Board=test" target="_new">http://www.amdragon.com/cgi-bin/w3t/postlist.pl?Cat=&Board=test</A>
I'm considering a hardcoded "file" Icon for posts with an attachment...
<img src="http://www.amdragon.com/images/eileensig.gif" alt=" - " />
