The only one that comes to my mind right now is PCGamer's official web-site, of course related to the PCGamer magazine, but even that site has less PC games-specific content then the "PC section" of a more generalist site like GameSpot or IGN, and to be fairly honest "PC gaming" per se is intimately linked to Console gaming, either we like it or not, and the lack of PC gaming-focused web-sites is just a testament of this reality.