A great read for anyone interested in delving deeper into game mechanics and how they define player interaction with both other players and the game state.
There's also PA TV's Extra Credits if you want a more informal discussion of game mechanics and design. The episode about balancing for skill was particularly enlightening for me.
http://www.penny-arcade.com/patv/episode/so-you-want-to-be-a-game-designer
Also check out Sequelitis; while not from a game designer, it still brings up some really insightful points about how game design can affect sequels to great games.
http://www.youtube.com/show/sequelitis
RIDIN' ON CARS! *MEEDLY MEEDLY MEEDLY MEEEEEEEEEEEEEEE!!!*