Gamasutra is a web site for people involved in ComputerGames. They have a lot of articles on programming, art, and sound, but also some on general GameDesign. All of the articles require a free registration. One of the most regular and insightful contributors is Ernest_Adams? with his "Designer's Notebook" column.
Gamasutra is run by the same people who do the Game_Developer_Conference? and Game_Developer_Magazine? (perhaps "Game Developer Website" was too long for a domain name? ;^) )