Buried inside this open-roofed enclosure (known as the Ohel) in Queens's Montefiore Cemetery are the sixth and seventh rebbes of the Chabad-Lubavitch movement, Yosef Yitzchok Schneerson and his son-in-law Menachem Mendel Scheerson (who was also the last rebbe, as he did not name a successor when he died in 1994).
Menachem Mendel (on the left, and often referred to simply as "the Rebbe") oversaw Chabad's worldwide expansion in the latter half of the 20th century. He was a particularly beloved figure in the movement, and some of his followers believed that he was (and some still believe that he is) the messiah.
All the pieces of paper you see lying in front of the gravestones are notes written to him, either by visitors or by people from around the world who have emailed or faxed their messages to the 24-hour visitors' center located at the edge of the cemetery in a house the Lubavitchers purchased after the Rebbe's death.
And what eventually happens to all the paper? "When the pile of shredded notes grows high, they are burned to make room for more; if you happen to come soon after, you’ll see embers of hand-scribbled petitions fluttering around at the foot of the Rebbe’s headstone."