Has anyone ever published on Amazon before?

Has anyone ever tried to publish and sell a book (novel, art book, ebook) on Amazon before? I'm just wondering what the process is like? Any tips or good sites are appreciated!

Also do you know if there's a way to make "print to order" books? (I was in this Meetup seminar and he was talking about selling coffee mugs and such, but IDK if it's possible with books.)