Last I saw, Google charges for this. More than this guy’s service.
Also, it seems like his service is about automatically having username-category email addresses. Definitely not hard to replicate, but it circumvents the common blocking of plus-signs in email addresses you see nowadays. And while not hard, it’s a bit less trivial to catch any old email with a dash in it and “magically” convert it to a category in the main inbox.
Do you know of any obscure useful websites?
SEO has essentially destroyed search engines, what are some very useful websites that you might not get given by Google?