Open Peeps - A hand-drawn illustration library.
Blurb - Create and self-publish books, magazines & ebooks
Control Illustrations - 108 free flat illustrations with customizable characters
CreateSpace - Publish your words, your way
DrawKit - MIT licensed SVG illustrations, in 2 styles
IngramSpark - IngramSpark is an Online publishing services provider platform that allows you to publish or print books that are in high quality, and its global distribution service enables you to post and share around the globe.