O’Reilly books on computer languages are well known for their distinctive book covers that always feature animals who are in some way connected to the theme of the book.
If you are writing a book for O’Reilly, their in-house designers like Lorrie LeJeune will do the animal sketch for you but for everyone else, try O’Reilly Maker.
It’s an online tool for generating fake animal book covers that look pretty much the same as O’Reilly designs. You can change the text, book color and the animal image. Good fun. Thanks Dion
Related: Put Your Photo on CNN or Magazine Covers