Two retailers already participate: H&M offers $10 back when you spend $75, and Sports Authority offers $20 back when you spend $50. At least four New York City restaurants also offer specials: Blue Smoke, Union Square Cafe, Untitled, and The Modern.

Foursquare said that it would announce other deals as the company signs up new partners.

Certainly, Foursquare faces an extraordinary amount of pressure as others move in on what was its signature feature. Striking deals like this one with American Express though broaden its appeal, which obviously is crucial if Foursquare wants to stay relevant.

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