I just happened to be online and checking my email when I got a Paypal billing notice thanking me for signing up with Skype. Which I haven't - don't have the equipment for it. Then there was a receipt for a payment apparently from a secondary email on my account to some gmail address I'd never heard of. And both were in Euros, which I've got no reason to use.
So I cancelled the billing agreement and, since the payment's recipient hadn't claimed it yet, cancelled that too. Then I changed my password, then I filed an unauthorized transaction claim on both of them.
So with any luck I'll be getting the money back, but until it's cleared up they've got a $30 or so hold on my checking account. Or at least they tried to, it hasn't hit my bank site yet but it might not until business starts tomorrow.