Foreshadowing in TGwtDT

"On the porch laid a half-charred corpse of a cat. The cat's legs and head had been cut off, then the body had been flayed and the guts and stomach removed, flung next to the corpse, which seemed to have been roasted over a fire. The cat's head was intact, on the saddle of Salander's motorcycle." 

-Chapter 21, page 435

One of the most apparent uses of foreshadowing in The Girl with the Dragon Tattoo is Blomkvist’s discovery of a dead and dismembered cat on the porch that hints at the violence that will occur later in the novel, as well as Martin Vanger's psychopathy. 

It can be said that great authors never write a sentence unintentionally, and that some books are even better after rereading. After reading a book, the reader knows most of the intricacies, outcome, climax, and plot twist of the book they had just read. So why reread? Because "things cannot be understood in isolation -- they have to be seen in the larger structures they are part of" (Barry 38). In other words, reread to look further into the story and better understand the use of foreshadowing and the unseen structure of the book, just as the author intended.