How many LivingSocial users can Amazon buy for $10?

Deal site LivingSocial has got a helluva bargain today: A $20 Amazon gift card for 10 bucks. Who could resist that? I could. Should you?

LivingSocial specializes in half-price deals, typically specific to larger cities -- assuming you live there. I went to the site for the first time early this afternoon. By Internet magic, most likely IP address, LivingSocial correctly detected my city as San Diego. I clicked through to see the big deal, the aforementioned half-price Amazon gift card.

So what's the catch? There's always a catch. LivingSocial gets your email address -- and also credit card number to purchase (What? There's no PayPal)? It's a "let's get 1 million email addresses in a day" deal. There aren't many marketing promotions better than this. People actually pay you to take their email address. "We email our deals daily. We keep your email safe with us," LivingSocial qualifies. I don't doubt the sincerity of the privacy policy, but it's still selling my email address for 10 bucks.

The site qualifies that "Amazon.com is not a sponsor of this promotion," which technically is true. So why does this post's title say "can Amazon buy?" In December, Amazon invested a cool $175 million in the Washington, DC-based startup, which began as a "Pick Five" app on Facebook. Besides, the Amazon gift cards are doing the buying.

So, will you give up your email address for $10. I'll keep mine, thank you.