The Email Game Wants to Make Achieving Inbox Zero Fun
gigaom.com/2011/04/12/the-email-game-wants-to-make-achieving-inbox-zero-fun
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Lame that these only work with GMail. Where is generic IMAP support. :-(