Foursquare. In World of Fourcraft users pledge fealty to a particular locale then, for the honor of their homeland, check-in to wrest control of neighborhoods from their residents and defend their own turf from potential usurpers. The whole project was whipped up last weekend during a hackathon at New York's General Assembly. At the moment it does little more than tally check-ins, but the creators plan to add new features in the future. Now, go forth and do battle for your block but, don't stray too far -- to the north and east of the Boogie Down Bronx, and the south and west of the Slums of Shaolin, lies The Waste Land.