The life of a self-described "photograffeur" and "urban activist" is an exciting one, judging from JR's Instagram feed. The 2011 TED Prize winner, who transforms public spaces into challenging works of art by flyposting enormous black-and-white photographic images onto buildings and streets, hangs out of helicopters, dangles from cranes, and rubs hands with Robert De Niro. Even though the work is frequently serious, the sense of humour in the background is almost as motivating.