If you build Web-based information systems -- and who doesn't? -- it's a great idea to  wrap them in Web services APIs. The more the merrier. By offering a choice between SOAP- and REST-flavored APIs, Amazon embraces diversity. But Amazon is even more inclusive than that. It gets the simple things right. The page that represents a book has a canonical URL that you can construct automatically. It carries basic metadata in standard HTML META tags. These rules seem too trivial to mention. But they are seldom followed, even though they can spell the difference between a healthy information system that integrates with a society of peers and an isolated outcast. Moral: do the simple things.