> Some websites have noticed that web site copiers like to
> surf in a layer type fashion instead of sequential
> fashion like a human would do when trying to reach a
> file, for example.
> human: link->setcookie->deeperlink->setcookie-
>stilldeeperlink->setcookiefile.zip
> robot: link, link2, link3...linkdeeperlink, 
link2deeperlink

Right - this has been discussed recently, but unfortunately 
it is very difficult to avoid this behaviour ; as cross-
links (links in depths, relinkink to "top" levels) will 
aldo "damage" cookie value and session state. Each link 
would have to be "analyzed" for that, and it is something 
really impossible to do :(