[Zope] defense against bots..??

[AM]

Hi,
My site features an image repository which is available for free to all. 
However one has to download each image by itself.

Is there a way to block download managers and miners like...
GoZilla
http://tribolic.com/webminer/ (web miner)
etc...

TIA
AM

-- 
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 Aseem Mohanty							   
 Neurobehavioral Systems Inc, 828 San Pablo Ave, Albany, CA 94706 
 (R) 510 7696011 (M) 510 3014871 (O) 510 5279231		  	
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 "I saw `cout' being shifted "Hello world" times to the left and  
  stopped right there!!"                        -- Steve Gonedes  		
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