It was a brave person who first cracked open a cow bone and slurped out the goo in the center, but God bless them for it: Fatty, melty marrow is one of the world’s great culinary finds. And New York chefs have been taking advantage of its amazing flavor — and relatively low cost — for years. (Heck, we noted that it had become a menu-must in 2009.) But chefs being who they are, they’re never content to leave well enough alone, thinking up all sorts of delicious new ways to put the stuff to use. So as the weather refuses to warm up, it seems like a good time to survey the city’s landscape and take a look at some of the newer additions to the marrow canon — and a few classic preparations that we just couldn’t help ourselves from including.