I'd give them the URLs but not be having it to *show* them. Why put yourself in jeopardy? (This goes right with buying drugs without police knowledge to prove the guy down the road sells it) They will pop YOU first...
Go to the yahoo page and shut that always allowed to ask link (it doesn't work 100%) but it stops the majority of requests to join. I have it set to NO and still get one on occassion. All they have to do is go into a group that has the addies showing in part and use a harvester. Or so I was told.