From Groupon's site: Groupon negotiates huge discounts—usually 50-90% off—with popular businesses. We send the deals to thousands of subscribers in our free daily email, and we send the businesses a ton of new customers. That's the Groupon magic.
It's free and super easy to sign up! You don't have to give any personal information - just an email address and a password that you pick. I've gotten so many different things with Groupon - but I've noticed that they mostly feature small/new businesses and often have organic, eco-friendly companies highlighted. But now that I think of it, they may send me the above mentioned deals because I specified that I was interested in those sorts of things in my profile! So they'll send you deals on things that fit your interests! How cool is that?!?!?
If you're interested in checking them out and signing up for their daily emails, click this link! If that doesn't work, copy and paste this into your browser: http://www.groupon.com/r/