> in the first place? Isn't the point of a mirror to
> have an EXACT copy?
A URL may not even have an extension and still be a valid file. 
<http://www.w3.org/Provider/Style/URI> (search latest)

Also .ASP .PHP etc are server side files.  Once downloaded you have plain
.html or in the case of file.php?get=image.XXX a XXX