I had the same problem with someone signing up for an Apple ID with my email address.
I even tried calling Apple to get them to cancel the account, but they wouldn't let me because I couldn't answer any of the security questions on the account!
The guy on the phone acknowledged that of course I can't answer them, because I didn't create them, bit their policy forbids them from doing anything without the security questions...
Man, now I'm wondering if this is some sort of violation of the CAN-SPAM act. My blood pressure goes up a little every time I get one of these emails and it doesn't have a way to unsubscribe if you aren't the legitimate recipient. Considering the companies that spam me the most with this irrelevant crap are Apple and Wal-Mart, I would feel 0% bad if they lost money over this practice.
Quick Edit: I just read the Wikipedia page, and individuals cannot bring suit against spammers (using CAN-SPAM in any case). Which is a shame really, because spam is really really annoying.
I even tried calling Apple to get them to cancel the account, but they wouldn't let me because I couldn't answer any of the security questions on the account!
The guy on the phone acknowledged that of course I can't answer them, because I didn't create them, bit their policy forbids them from doing anything without the security questions...