This doesn't cost you a thing. Their corporate sponsors /advertisers use the number of daily visits to donate mammogram in exchange for advertising.
Here's the web site! Pass it along to people you know."
Confirmation of this is available at http://www.snopes.com/inboxer/charity/mammogram.asp
P.S.- I don't think they're having trouble getting people to click. And I'm sure as hell not going to order any of that junk with pink ribbons on it. But, I am keeping the page open in firefox. Every time when I reboot my computer, I'll give it a click a day for quite a while. It's easier than giving quarters to bums, and its for a better cause.