Tiny Speck's browser-based MMO Glitch closed late last year, but a recent addition to the game site's encyclopedia adds almost 200 internal design "Quick Ideas" from designer Keita Takahashi.
These notes not only prove that Glitch was (and could have further been) a truly unique MMO, but they show why Takahashi was hired in the first place. OK, Katamari Damacy probably had something to do with it I guess.
If you were (and are) a fan of Glitch, this is certainly worth a look. Be prepared for the sads.