I spotted one of Luke Jerram's 30 pianos, but was too shy to play. Pianos occur across London as part of an interactive art project to challenge people to come out of their urban insularity and also to provide some summertime music.
Eric W. Sanderson's Mannahatta Project, an exhaustive study and recreation of the Manhattan ecosystem circa 1609 (the year of Henry Hudson's arrival in Mannahatta), as an exhibition at the Museum of the City of New York.
nick goddard arranged the unemployed olympics in new york. an opportunity to "battle all the unemployed people for stuff" in events like "pin the blame on the boss", "you're fired race", "and pay days" (bashing a pinata with an office phone).