Issuers are clamoring to pay you hundreds of dollars to get you to sign up for a card with zero interest for 18 or 21 months. And I see no reason not to do it....
Rewards programs cause cash-using households, which also happen to be lower-income, to subsidize card-using households, which are also higher-income....
AmEx brings social sopping to the UK and I expect that the Brits would be just as keen on the Foursquare deals as we are on our side of the Atlantic....