>  response for
> www.thecoverproject.net/download_cover.php?file={mis
> c}.jpg:
>  Content-Disposition:
> attachment;filename={misc}.jpg
>  Content-Type: application/x-download
> in the headers but I don't know why HTT still saves
> the file type as .php locally.
Exactly the reason. It should return content type=image
but doesn't so httrack doesn't know what to do with it, so it keeps the .php
extention.

> Headers also show that the server does not report a
> "Content-Length" for a download_cover.php request. 
> Because of this, I am presuming, trying to filter
> (include OR exclude) by size fails.  Too bad because
> some of these are big-ass files :)
have to download to get the size.

> I also noticed these headers:
>  Expires: Thu, 19 Nov 1981 08:52:00 GMT
>  Pragma: no-cache
>  Cache-Control: private
> I'm sure not if it's related, but HTT seems to think
> all these files have never been cached and need to
They have never been. The server is sending the image in the return stream,
not redirecting to the actual file with a real mime type. Therefor the content
is NEW each time.
Total waste of resources.