Restaurants can tip YOU (the customer) using Groupon

I just watched a 1 minute Groupon video the blew my mind because it explains how merchants can rate and reward their customers via Groupon.  I don't know of any other site that allows this .... Please comment if you know of one.

There are so many good things I can say about this company and it's business model that I don't know where to start.  Here goes ......

1. Awesome deals.  Groupon has built it's business on collective buying power.  A steeply discounted deal (always greater than 40% off) will be offered within a geographic area every day.  If a minimum number of people agree to purchase it, the deal will be released.  Sign up to get an email every day for the deal of the day in your area.  Here is a that explains how they work.
2. Awesome businesses.  Groupon has some of the most exclusive businesses participating.  Some of the restaurants I have purchased, I have never seen a coupon for ... ever.  If you know me, you understand that I take coupons and deals very seriously.  Some of my favorite exclusive Groupons include Sushi Groove and Supperclub in SOMA (although supperclub participates in restaurant week, it's usually too hard to get a reservation).
3. Seamless referral bonuses.  Apparently someone joined Groupon because of me- I didn't even know!  The next time I purchased a Groupon they automatically called out that I was saving $10 on this purchase because of my referral.  I didn't have to dig up a coupon code, hidden 3 pages deep within my account activity.  Nor did I have to mail a receipt with 3 forms, wait 6 weeks, get a check in the mail, and have to make a special trip to the bank.  They just gave it to me.  I love when a business make my reward seamless and automatic. 
4. Merchants can rate customers.  Not only do they give users the opportunity to rate a business, but merchants can rate customers!  If you are good tipper, become a regular, or compliment the chef, they may rate you positively so that other business can see you are "good people".    It will be very interesting to see what happens now that merchants can rate, reward, and respond to the clientele that they serve.  As a former server for 6 years, there are several occasions where I would have loved an opportunity to provide feedback on my customers :)
   
   To make this deal even sweeter, when a merchant gives you an "award", you get Groupon bucks to use toward your next purchase!  Here is a page with tips on how to be the type of person an establishment would award.  Groupon Etiquette