Blocking doubleclick with Apache proxy (Score 2)

I run an Apache webserver/proxy and added these lines to httpd.conf to block doubleclick ads:

<LocationMatch "http://ads*\.">
RedirectMatch 301 .* http://www.mysite.org/empty.png
</LocationMatch>
<LocationMatch "http://[^/]*doubleclick">
RedirectMatch 301 .* http://www.mysite.org/empty.png
</LocationMatch>

Maybe not as versatile as junkbuster, but it saves an extra proxy step.