I made up my own design instead of using an existing book cover, because I found none that suggested themselves to me for a word cloud. The texture and colors are supposed to be reminiscent of a communist flag, and hopefully it's obvious that the cloud is in the form of a pig's head.
Once the trivial words are removed, the list contains mostly character names (Napoleon drives away Snowball, and thus his name is mentioned more times), types of animals (pigs, hens), farm features (windmill, barn) -- and then the words that remain are very evocative of the character of the book, such as comrade, orders, rebellion, commandments and orders.
This is a short book, at about 30,000 words. There are 3,900 individual words, but once the Porter Algorithm is used to identify word stems (so that "thinking", "thinks" and "think" are counted together, but "thought" is not -- it's an imperfect algorithm but it produces about as many false positives as negatives, and is more than reasonably accurate), the number drops to 2,900 words.
The title occurs 43 times, and the book has an oft-recurring six-word phrase: "four legs good, two legs bad" appears 13 times. For 0.25% of all words in a book to be the same six-letter phrase is highly unusual, especially without any of the words being as common as "the" or "and".
The words used only once are similar in character to the most common words: the personal (Simmonds, Caesar), pastoral (matchwood, piebald, stockbreeder, windowsill) and atmospheric (tunefully, conciliatory, bloodshed).
Animal Farm on Wikipedia
IF YOU DON'T LIKE THE ANIMATED GIF, SCROLL FURTHER DOWN.
Again, I could not find a book cover or movie poster that spoke to me for a word cloud. I was fooling around with some typography and came up with the following:
I wasn't sure it was clear that the background of the word cloud was supposed to be static, so I animated it.
The progatonist's name, Winston Smith, features heavily (526 times), as does that of his antagonist, O'Brien (205). Julia's name appears less than half as often as O'Brien's (100), but to be fair Winston doesn't learn it until partway through the book.
Nineteen Eighty-Four is famous for the introduction of newspeak, but those words appear relatively little: doublethink is used 30 times, compared to telescreen at 92 and Oceania at 60. Speakwrite and thoughtcrime are used 13 and 11 times, respectively.
Like Animal Farm, there is a long, repeated phrase: "Oranges and lemons, say the bells of St. Clement's" appears eight times -- exactly as often as the organization of which Julia is a member, the "junior anti-sex league".
There are many more common two-word phrases such as the culturally iconic "Big Brother" (78 times). The word "party" appears 70 times in recurring 2-grams such as "party member" and "inner party".
"Two and two make five" appears three times.
Among the words used only once are bastards, homosexuality, tribunal, silk, monopoly, romantic and intercourse.
The book is 100,000 words long; there are 8,500 individual words and 5,700 unique word stems determined by the Porter algorithm.
Nineteen Eighty-Four on Wikipedia
Word cloud created using Tagxedo.