Amazon started to display SIPs (Statistically Improbable Phrases) for books. In a nutshell: the SIPs for a book is a collection of terms or phrases within this book which are most unique in comparison to all other books (see Amazons definition here).

The SIPs for Getting Things Done for instance are: your open loops, nonactionable items, natural planning model, next physical action, defining your work, your action lists, reference filing, action reminders, organizing you, collection buckets, daily files, tickler file, mind like water, project thinking

- which actually isn’t that bad and would make a great reference for picking essential but not utterly obvious tags for various resources, if this service would be available for them as well. (SIPs for e.g. Blogs would be great.)

via del.icio.us/plasticbag