The social media world is changing the way we live and work. It's fun to use apps like FourSquare/TopGuest to earn Hilton and IHG points (plus Virgin America and others). Are there any other social media outlets that award points regularly? I know that Facebook and Twitter often have special promotions for one-time earning, but is there anything else that offers regular earning opportunities?

I noticed that GroupOn is now in the Delta Shopping Mall. Have people had success earning miles with it? Any other places to earn miles for our daily activities on social media?