I am not a person who always talk about deals or promotion.
But I can't resist this time.
By using your Facebook or Foursquare account to check-in at a participating airport, you can either earn 50 miles from Continental OnePass or United MileagePlus.
The links to register are below:
Why am I mentioning this?
It is related to my recent commuting arrangement. As I have to pass through US 101 each day (which San Francisco International Airport is next to the freeway), basically I just simply check-in without going into the airport (I don't even have to stop...)
And Voilà - 50 miles per day...(and it works...)