How do I create a QR code for email sign-ups?

Looking for a way to create a QR Code that we can print on an 8 1/2 x 11 piece of paper for our register counters. The QR Code would allow new to easily sign up for our emails through some kind of a link that lets them add there own email into one of our existing lists on constant contact. It would also be nice if once the new customer adds there email to our list they then get an automatic email sent to them that would have a coupon in it or attached to it for there next visit. Any help with this would be awesome.