>  (Off topic again, but lots of people here are using reverse
>  proxy).
>  
>  For a while I had 'ProxyRequests On' in my httpd.conf mistakenly
>  thinking that it was necessary to make ProxyPass and mod_rewrite
>  proxying work.  Then I noticed entries in my logfile where
>  remote sites were sending full http://requests to other
>  remote sites.  I've turned off the function, but the requests
>  keep coming in, mostly appearing to request ads from somewhere
>  with referring pages in Russia and China. 
>  
>  Is this a common practice and what are they trying to accomplish
>  by bouncing them through my server? 

Yes it is very common practice, and so is scanning for open proxies
on ports 80, 8080 and 1080. Here's a link to a list of open proxies
and a faq that explains their use.

http://www.cyberarmy.com/lists/proxy/

--
Eric