If you don't speak German well enough to read the two Jünger biographies that came out more or less simultaneously in 2007, then here at least is a good English review of Helmuth Kiesel's one, Ernst Jünger. Die Biographie. It is by Eliah M. Bures, Department of History, University of California Berkeley.
PDF print version
(Mr. Bures will talk about Jünger April 23 in Berkeley as part of the (Re)Making Myths conference. His title: "Leute von Übermorgen und von Vorgestern”: Myth and the Construction of Community in Ernst Jünger’s Postwar Imagination")
P.S. The other 2007 biography is Heimo Schwilk's Ernst Jünger: Ein Jahrhundertleben. Schwilk knew Jünger personally and was an admirer, so this one is more personal and intimate, while Kiesel's is more rigorously academic. Personal acquaintance and sympathy as a advantage in biographers? No comment, but in any case you can guess which I prefered.)