James Pardey's ode to Penguin science fiction book covers may take a while to load, but the wait is worth it. He's put together a definitive collection of the publishing house’s sci-fi covers, from it's inception in 1935 until the present. Searchable by author and year (don’t overlook the link to the table of contents in the upper-left corner of the home page, or the index link at bottom-right), the site contains short descriptions of most books, articles about how book-cover design at Penguin changed over the years, and sets of different covers for many titles. There are three versions of “The Invisible Man” by H.G. Wells, for example, and 14 of “Nineteen Eighty-Four” by George Orwell.