FriedSPAM: The legality of this is deeply questionable:
“Let FriedSPAM visit [spammers] sites for you — about a million times! After all, you are only doing what the spammers are asking you to do. Just enter the URLs of the websites that the spammers want you to visit, and hit START. After that, FriedSPAM will do the visiting for you, as many times as you want. Let FriedSPAM visit while you sleep! That’s what the spammers want, isn’t it? After all, why else would they stuff your mailbox with such tempting invitations?”
I love the “Interval between visits” box. Thank God the minimum is 100 milliseconds — I was afraid this site would let you do something irresponsible.
It uses client-side VBScript, so you need to leave your browser open while it hammers some site. Additionally, this lets the site owners out of some sticky legal issues since YOU are the one delivering the traffic bomb.