I run a photography site for a commercial photographer and 
it seems that people assume with two photos of women on the 
site there must be porn to be had, so we get hit with 2-3gb 
of transfer a day. Over and over again, we keep seeing this 
as a problem. As great as the program is for digging for 
porn, which let's be honest, that and warez is what it is 
used for, there has to be a deterrent or remedy for this 
gross violation by folks that just think photos always 
insinuates something pornographic. 

We are using an htaccess file to prevent hotlinking by 
swapping unauthorized domains swapping the requested image 
with a spacer.gif. That has dropped our bandwidth by less 
than 5% overall.

The temptation to use a dropdown and form will help 
slow 'some' less knowledgable users, but there needs to be 
a better way.