They are 'hacker' programs that scan web pages for email addresses mostly (the "mailto" HTLM code is a GREAT target)
They then collect the addys and supply them to people who send out all that lovely "Make your Dick bigger overnight" spam that clutters up the WWW....
I've seen NO indication that they harvest "Real Names" off the net.... Too labour intensive to be worth much... You'd have to be pretty thick to want to set such a bot up, or to be afraid of one.